Another to thing to think about is a converted school bus. I have one. Flat nosed Blue bird. 8 liter turbo diesel allison auto in it.

10.5 mpg at 65mph. The car and a quad will fit in the back of mine. it sleeps 6. Plenty of room to move around too. Granted it is 45' 4" long but hey... when I am doing doing mine it will have a generator, fridge, air compressor and a few other amenities. If i really wanted I could put a hitch on the back and still tow my trailer with a second car.