We've done it several times...a few end-to-end trips and some shorter stretches. In a 32 foot class C and never a bit of problem with the road.
Last year we did a stretch of Skyline Drive in mid-October.....crazy busy......I had badly underestimated how many people were interested in fall leaf watching!
That was the only time I didn't enjoy it...trees were beautiful but so many people had the road and all the turnoffs packed...made it tricky to find enough room to stop. Compared to mid-October, the place is deserted in July and August...