THE GREAT AMERICAN road trip still embodies that freedom so deeply rooted in our culture: uninhibited, spontaneous, independent—until you have to sleep, that is. Various options exist for roadside snoozing, from cookie-cutter motels to lumbering RVs. Lately, however, more travelers are embracing an old-school solution with a twist: perching tents atop of vehicles instead of pitching them deep in the woods.
Spending...