If you're boondocking in the northeast, where there are lots of trees, I suspect the extra height would be at least as much of a problem as the extra ground clearance reduces. Most forest service roads are not exactly actively maintained with regards to overhead clearances for tall and wide vehicles. Likewise the width and length of a large fifth wheel will pose problems on many such roads even if the height and ground clearance are okay.
Things are different in the plains and many areas of the west, I suspect, where it's far more wide-open.
A little trailer, suitably set up, or a pickup camper seem to me the most effective back-road RV (at least that could be afforded by a person of more or less ordinary means).
