My cousin made one like that, you can see it a little here


They found out that they did need AC as it works like an oven in the sun, so you need to insulate it well.
They covered the inside in plywood like normal then hinged another sheet of plywood to fold up on the side so they could haul their 4 wheeler or fold it down for the bed.

It doesn't handle real well off paved roads though, not a lot of ground clearance, have to spot and go slot a lot to look for the hitch or rear to drag. Thats what steered me away from a trailer to a truck camper.