I've booked campsites before with limits of 20 ft and had no problems. BUT, I look for more information, if they supply it, and at pictures, again if supplied. Some will state a 20 ft limit but have a 35 to 50 ft driveway. Go figure. Look also for ease a access, a limiting factor for back-ins, which could be an indication weather or not there are obstacles, like trees near by. Some will also state the overhang available. This is the area available behind the limiting barricades that stop your trailer wheels, but not your trailer. The last thing I look for is how level the parking pad is. The driveway could be long with a short level parking area. Good luck.