I have been down gravel roads (a lot of campgrounds only have gravel roads - and some with potholes) and have driven in grass fields. i have been on a few regular roads with large potholes. You go slow, you avoid the holes, and watch for sudden drops. The ground clearance on many Class Bs is low and there is a lot hanging down that can be expensively damaged. You have to watch out for deep mud too. There is nothing like getting stuck with the wheels spinning digging you down into the ground. If you are careful you will be fine.