We have a 40' motorhome towing a 22' car trailer. Bumper to bumper is 65'. When we make reservations, we ask for a 65' pull-through. We don't need anything longer than that because it only takes a minute to open the ramp door and back the car out. We close the ramp door and go sight-seeing. When we come back we open the ramp door and put the car back in the trailer.
If a pull-through is not available, we ask if there is a place to park the trailer separate from our site. So far, we have not been turned away anywhere because of the 65' length. It helps if the car that you are hauling is able to move the trailer around.