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1970 Avion C11 truck camper rounding a corner in the road in Colorado National Monument with colorful rocks and scrub brush in the background.

We love truck campers. Their size, flexibility, and convenience had us sold long before we found our 1970 Avion C11 slide in. But there is one very notable downside: storage. Sure, we already knew our camper would be on the small side. But, there’s a lot of potential storage lost where the camper body cuts in to make room for the truck bed’s wheel wells and walls. That actually adds up quite a bit of unused empty space (how much, we’ll get into later)

So, we are finally doing something we’ve been talking about for years: commissioning a custom truck bed. “Commissioning?!” You may well ask. “Why, isn’t our raison d’etre to do it ourselves?”  Certainly! But, as much as we are eager to learn new skills, we recognize our limitations and the cost of tools to overcome them. We learned to weld a few years ago, but only enough to recognize the extreme time and effort it takes to master this skill. We’ve accepted that welding is our limit. So, we are deferring to professionals to build our truck bed and collaborating on the design.

Unlike our factory bed, we want to start with a flatbed with under bed and over-bed storage boxes. The bottom boxes will be relatively standard but the top boxes will be designed to fit in the negative space left by the camper.

To start, we need to establish the dimensions of the camper that the new truck bed will support. The closer we can get to exact measurements, the better we can optimize our storage. To do this, we take our camper off the truck for accurate measurements.

Cross section view of a 1970 Avion C11 highlighting the lower walls and floor.
Cross-section view of the 1970 Avion C11 exposing the walls that will come in contact with the custom truck bed.

In measuring the camper, we confirm one unfortunate fact that we had anticipated to some extent: the camper isn’t perfectly symmetrical. The variations between each side is small but significant in terms of this build. This is, after all, a hand-built structure constructed in 1970. (Well, likely 1969). And, despite my best efforts when rebuilding the base, there are some inconsistencies that quickly became apparent.

Height / DepthWidth / LengthWidth / Length (alt)*
Floor48½”100⅛”99¾”
Driver Wing21½”100⅛”
Passenger Wing21¼”99¾”
Driver Side Wall20″**100⅛”
Passenger Side Wall20″**99¾”
Driver Rear Wall20″21½”19½”
Passenger Rear Wall20″21¼”19¼”
Camper Wall Dimensions

*Alt measurements are only relevant in cases of inconsistent measurements such as the rear walls which are cut at an angle.

** Measurement reflects the height of the physical wall. Not the distance from the truck bed floor. The truck camper sits on a set of three rails that lift the camper an additional ½” to ⅞”. Yeah, that was a little inconsistent since it was one of our first projects when renovating the camper and attaching the floor to the side walls was an awkward affair.

Cut outs of the camper walls with dimensions labeled.
Break down of the dimensions of each camper wall that comes in contact with the truck bed.

Truck Bed Dimensions

Before we can start building, we need to settle on the dimensions of the truck bed. Some are out of our hands, such as practical requirements to fit on our 2015 Ram 3500 Tradesman truck, accommodating the wheels and tires, and remaining road legal. But along with that, we have a lot of options. Some dimensions are dictated by practicality. We want a lot of storage, after all. But some of it also comes down to aesthetics. It would be a shame to have a clunky truck bed after all the work we’ve done on such a stylish camper.

Bed Length

The Avion truck camper establishes a hard cutoff on the length of the truck bed due to the fiberglass basement that hangs below the subfloor and stores a couple of tanks. Obviously, the truck bed can not travel beyond that point, which gives us a working length of 99¾-inches from the bulwark of the camper to the beginning of the subfloor. (We’ll slice off a half inch for wiggle room.) Add to this a few inches of transitional space from the truck bed to the cab. In total, this makes for a truck bed length of 103¼”.

Bed Width

Similar to the bed length, the bed width mirrors the dimensions of the truck camper. The bed width at the foremost point of the bed will mirror the width of the truck cab, about 77-inches. It then angles out to mirror the flair at the Avion’s bulwark. For this width, we are looking at the base tapering rear walls and subfloor and measuring the width of this part of the camper at the point where the truck bed would sit. This turns out to be 87-inches.

Deck Depth

Our goal in the design of this truck bed is to keep the camper at the same height relative to the truck cab. As such, this bed is not meant to have the wide, raised look of most flatbeds. We want it to sit as low as possible on the truck without sacrificing its structural integrity. At the moment, it looks like that means the bed will be 4-inches thick.

Max WidthMin WidthLengthDepth
Truck Bed Deck103¼”77″87″4″
Storage Box Dimensions
Diagram of truck camper flat bed from 1970 Avion C11 truck camper
Dimensions of flat bed base.

Upper Storage Box Dimensions

The upper storage boxes will fill the negative space between the truck bed and the camper wings. Our plan is to make these upper boxes removable so that they will be out of the way while mounting and unmounting the camper.

Box Width

In an ideal world, we would create boxes that perfectly fit the camper and used every inch of space. But, anyone who has mounted a truck camper knows how difficult it is to mount a camper. We need some wiggle room to mount the truck bed under the camper.  Currently, we have four inches of wiggle room between the wheel wells and camper body and that’s worked well enough that we’ll reproduce that spacing between the new box. So, our camper floor is 48½-inches wide, plus 4 inches, for a 52½” distance between the boxes.

With that in mind, we can settle on the width of the boxes. A cross-section of these boxes will roughly mirror the rear walls of the camper while taking into account the extra wiggle room of 2-inches on each side for the camper. This means that the greatest width of the boxes will be 19½” on the driver side and 19¼” on the passenger side while the boxes taper to 17⅜” on the driver side and 17⅛” on the passenger side.

Diagram cross section of a truck camper and storage boxes under its wings.
Cross-section of the camper and upper storage boxes.

Box Height

Returning to our ideal world, the upper storage box height here would mirror the distance from the truck bed floor to the camper wing. On the driver side, that would be 20½” (19¾” side wall + ¾” rail) and on the passenger side it would be 2¾”” (20″ side wall + ¾” rail). But we need some wiggle room.

Max WidthMin WidthHeightLength
Driver Storage Box19½”17⅜”20¼”TBD
Passenger Storage Box19¼”17⅛”20¼”TBD
Storage Box Dimensions
Floor plan diagram of upper truck bed design.
Overhead and side views of the upper truck bed.

Truck Bed Features

Along with the core deck and storage boxes. the truck bed also has to accommodate a few other considerations. For starters, the gas intake for the truck is built into our current stock bed and will have to be replaced for this new, custom bed. Because we have such a low deck, We need an elevated intake to ensure that gravity can pull the gas into the truck’s gas tanks. So, that will be built into the Driver’s front storage box.

Also in the driver-side front storage box will be the alternator charger, a key power source for topping up the batteries in our camper while on the road.

Camper Modifications

Now that we have the truck bed design set, there’s some alterations we will have to do to accommodate the new truck bed.

Jack Points

We have one problem point: our jack points. These angle brackets are critical for loading and unloading the camper but they will get in the way of our proposed boxes. We could make space for the jacks. But that’s potentially messy. Instead, we’ll be creating a way to remove the jack points when they aren’t in use. Right now, the jack points are bolted to the camper wings. Now, we’ll be designing an alternative.

Illustration of passenger and driver camper wings and placement of jack brackets.
Dimension of passenger and driver truck camper wings and placement of jack brackets.
Brophy tie down, turnbuckle, and camper jack point.
We also use the jack points to tie the camper to the truck bed. That’s another thing that will need changing.

Tie Downs

With the jack points gone, we are also losing our traditional tie-down points for connecting the camper to the truck. Fortunately, with the current truck bed walls replaced with new storage boxes, we will now have access to the base of the camper where it meets the truck bed. We’ll be installing angle brackets to the bottom edge of the camper to bolt onto the new truck bed.

Lexi lives in a truck camper down by the river.

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