It is not so much a campground not willing to take your money and accept you, it is the ability to get it parked without damage to the rv in a lot of smaller am and pa style campgrounds.
When you start getting into that are it becomes tougher to find a spot to get parked. The campground I often stay at had 4 sites that can fit a 40 footer or more, two are taken by seasonal and two are for over nighters. These same spots are used by the 35 foot guys so yes you could get turned away from a campground like that but would think it would be rare.