I've finally started this project, something I've been meaning to do for a while -- the BRAT has plenty of storage in the truck bed, but no place to sleep on road trips. Now that I've got a camper shell, time to fix that -- I know I can (and have) fit in the bed to sleep easily enough, but truck beds are pretty uncomfortable places to sleep, and I've usually got gear in the bed anyway. Setting up a tent every night on a weeklong roadtrip gets annoying (been there, done that), so it's time to make a microcamper! If you google around, you can find plenty of awesome builds, with gigantic drawers that pull out of trucks, everything and the kitchen sink -- I don't really have room for that, and I'd like to start simple, something I can complete in a weekend or so and then use, I can (and will) upgrade it later (the other advantage to simple is weight, I like getting good mileage).
The first iteration is going to be dead simple -- some supports to hold up reinforced plywood divided into three sections, this gives me a raised platform with storage underneath. A memory foam mattress on top, and the deck should be perfect for sleeping and light storage for whatever I can't fit under it.
Aside from the BRAT and the topper, almost everything in this project was free -- my landlord was trying to get rid of some lumber so I only had to buy a 2x8 and a 2x4, and the most expensive parts were 8 angle brackets to hold the supports/benches together -- I could have gone cheaper and made wooden triangles to support the benches, but the steel brackets maximize space.