Good luck with that idea. We've done that. My wife and I took our son and two grandsons from La Crosse, Wisconsin to Washington, DC and back, over 2,000 miles total. A Class B is not designed to sleep 5 inside the shell and probably 4 at the most. Then you block every door and can't move around easily. You will overwhelm your facilities. You have to carry extra baggage for every passenger that most Bs have no space for. The most practical way is to take a tent along which requires sleeping bags, etc. If you do that you might as well travel in a more versatile minivan with tents. This was a one-time event never to be repeated again. We used a tent.
Riding on a back electric sofa/bed with three seat belts. Lots of electronics to keep kids occupied including the TV with DVDs.