Forget the wall, we're gonna build a bed.

And it will be the cushiest bed ever to be installed in Annie. That I can tell you...bigly.
Any bed needs well defined borders. Otherwise, it ceases to be a bed, and just becomes a collection of lazy stuffed cushions. It also needs to be framed with good old American support. But the frame itself can be from China.

So we started off following the suggestions of folks who have used Harbor Freight 'cycle/ATV ramps as the bed frame, which will be proudly supported on the walls of the American made Transit.

The plan is to support the frame on some angle bracket bolted to the walls
Test measuring:

The frame itself is just a bit short. The frame's tailgate brackets are a bit long. What to do? What to do?

I decided to make some inserts that would fit in the frame and extend out the right length.
Something like these:

 OK, exactly like those. But with mounting holes to bolt to the angle bracket.

And placed the the frame with VHB tape and pop rivets.

I'm using 2 " aluminum angle bracket (1/8" thick stock) sandwiched between the wall coroplast and the wall. I'm using the existing coropalst mounting holes, but stuffing them with 1/4-20 jack nuts.

Drilled out the holes in the channel, and bolted it up.

I need the frame to be 74" from front to rear. Each ATV ramp comes as 3 hinged sections. 74" works out to 5 sections, or approximately 1.6666666666666666666667 ramp assemblies. I removed one ramp section by having it watch this election cycle on TV, until it became partly unhinged. (I used the left over section in the test measurement photo.)

The ramps now fit on the support channels, so I drill out the channel, and bolt them together. Using 1'4-20 bolts and nylocks.

The frame is installed.
As you can see, the label on the frame reminded me that I had to ramp up our efforts by adding support slats for the mattress. We will want to provide adequate air flow to the mattress bottom, since a camper is a small enclosed, often humid environment.

I cut 2" wide slats from a sheet of 1/2" ACX ply, sanded and varnished them. Then I pre-drilled them to screw into the frame

Busy screwing up:

Using 1/4" thick cedar strips and 3M 90 on the remaining exposed frame members. That gets all the slats at a common height.

Frame is done:

It's time to make our bed so we can lay in it.
We got a 7" memory foam mattress. It comes very squashed.

But the head of the aesthetics committee quickly determines that it will be an excellent embedded firmware/software solution.