There are plenty of well maintained, graded and graveled forest service roads that are suitable for a camper. On the other hand there are plenty that are not well maintained. If you have a 12000# camper that is 8' wide and top heavy, you need to be cautious. Mine is not that big but I still have a rule of thumb. If the road is suitable for an average car and there is clearance above, then it is likely suitable for my camper. If it is too rough, rutted or otherwise unsuitable for a car, then I avoid it with the camper. If you want to travel on back roads, you need to consider a small, light camper, preferably a popup.
