Yes, but what vehicle would you load a tandem, and two singles INSIDE and still have room for two s and two teenagers?
That would be my ideal solution, but I think the only option there would be a full size conversion van (and my wife grew up with one and refuses to get one). With the rear seat out, the tandem should be able to slide between the middle captain's seats and maybe have room behind the captains seats for the two singles.
Until then we're going to stick with putting them up top.