I once met a guy who was 6 feet tall and lived in a Volkswagen bug :).
He had taken out the rear seat and passenger seat, and put in a platform. For guests, the platform had a hinged section behind the drivers' seat -- he could take out the seat ("Two bolts!" he said), fold down the extra bit, and have a platform the size of a double bed. His stuff was all under the platform.
I met him on a ride share board, and originally was just going to catch a one day ride with him to another city, but we had so much fun travelling together that the trip grew into 6 weeks, boondocking and visiting friends. I wonder what ever happened to him.