You know when you have a bad experience with a campground, you remember it and unfortunately for KOA I had a horrible experience with them also and while it was one owner who I feel cheated me out of $35. and while $35 is nothing, that was in 2005 and I let my membership expire and I have never been back to a KOA since. I know it is silly, I don't blame all military base FAMCAMPS for one bad experience, but I won't go back to any KOAs ever.
Sorry OP you had a bad experience and charging you $40 to park your rig sounds absolutely ridiculous but now KOA has another unsatisfied customer and like me, you will think of it every time you think of a place to stay. What is that saying about cutting off your nose to spite your face.? I think KOA does that often.