Rent a cabin when you go! all the fun, none of the upkeep of the vehicle.
cabins in Custer State park SD sleep 4, $44 a night plus Nationl parks reservation fee; cabins in Estes Park Colorado $86 a night sleeps 8, have propane lights heat & 3 burner stove, oh yeah, and a porta potty.... I see in the eastern states you can stay at YMCA camps and such.
A cabin is the way to go if you don't want to tent.