So, this is an idea I know I've mentioned on other platforms, but one thing I've been a bit interested in, even though I don't have that much use for one, is camper vans.
Modern versions aren't exactly popular in the US, but they are popular in Europe, and quite a lot of people pay insane amounts of money for old Volkswagen Westfalia Campers.
The VW T3 Westfalia had a layout that many later camper vans have copied, with kitchen and cabinets on one side, and a bench that folds into a bed.