I just remembered my father's camper. That's it behind my first car. It was a 1948 Chevrolet Sunbeam Bread delivery truck. He painted it Oxide red and bolted the rear doors shut. It had double bunks across the back and a cabinet down the driver side that had a sink (fed from a 5-gallon milk can stood in the footwell) and a recess for a Coleman stove. And a Buick AM radio bolted to the ceiling.
With some generic commercial signage for urban camouflage it would make a tolerable low-key rolling home. It definitely wasn't an Interstate cruiser.