Go to any RV directory online and see how many places have unlimited length pull through campsites. They do exist but 99% of the time they will be private RV parks where you will pay twice as much as at a public campground.
Friends traveled around for years with a 28' 5th wheel and sold it and bought a 35' one. They regreted the decision on their very first trip as the extra 7' in length greatly reduced the number of places where they could stay.
Many campsites will be long enough but will require a tight turn and a 65' long tow vehicle and trailer combo will simply not make it.
Personally I find it hard to understand why people think they want to go "camping" when they need to also take every single creature comfort they have at home along with them on the road. Got to have the king size walk around bed. Got to have the full size fridge and freezer. Got to have the 42" television and the satellite dish. Got to have the full bath and shower. Got to have two high power AC units. Got to have a generator to power it all. This is not camping but cocooning.
