A 32ft MH is a good size for most places. My experience says NP CG's tend to be smaller than NFS CG's. SP's very by state. I live in the east and they are smaller than the ones I visited out west. It is not so much the length restrictions that are the problem but rather getting into some of these smaller sites. I have backed into tree limbs and damaged my ladder and AC covers trying to get into some of these small forested sites. I have a 33 ft MH and traveled to Alaska with a full timer with a 38 ft DP, we camped at a lot of remote places along the way I would go into the GC first with my MH and then radio him if it was large enough for him to negotiate the roads and sites. Most of the time we found sites that would accommodate us but there were a few CGs where we moved on. Arriving early increases your chances of finding larger sites.
