You will have a hard time fitting that many people and beds (particularly bunk beds) into a relatively short class C.
Frankly, the length probably makes the least difference in actual driving when compared with the height and width. On the road, the length matters mostly when merging or passing, and one usually doesn't pass too many vehicles when traveling in a motorhome. A longer unit does require more care when maneuvering around gas stations, parking lots, or campsites, but it's easy enough to compensate by going slowly and carefully and getting out and looking (and/or using spotters). Driving any of them is somewhat like driving a U-Haul, except the seats are usually more comfortable and the visibility out of the motorhome usually a little bit better.
IMHO bunk beds as commonly implemented in motorhomes are not as nice as they would at first seem to be. Many are pretty short and scant on space, while cutting rather significantly into the room available for other parts of the RV--those parts that you use when you're awake, like the kitchen or bath or living area. That said, I have seen one or two nice bunk layouts, including a really neat old Gulfstream layout (unfortunately in an RV that had been severely neglected) where the rear bedroom area had bunk beds on one side and a little second dinette on the other side, which would have worked out pretty nicely with a crowd.
