So I had to re-read your post to see your looking to see if size is a problem in sites. We have a 34' bumper pull and a Ram 3500 crew cab long bed so we are about 58' overall. I have traveled from Oregon to Washington DC, up in PA, Jersey and all over the NW with little problem locating a spot. Keep in mind most places you can hand the back of the trailer over back blocks in a camp site so you can get quite a bit more room.
Also if you book your sites in advance you can pick out where you like to camp and site size. In the west you can use BLM and NFS areas and camp for free in remote sites where size is definately not a problem.
I see you are in the south east so I would definately pay attention to the air conditioning on the rig. When it gets over 95 degrees mine has a hard time with the single unit but mine is an open unit so we cool/heat the entire unit.
Hope that helps to answer your question.