I read all the fine print on this location, but was turned away after driving 5 hours and getting into Las Vegas. They asked what kind of van I had, and immediately cancelled my reservation since I do not have a sink in the van. I did not feel this made any sense, since this location claims to have restroom facilities.
Maybe you could include the sink requirement in the reservations page, and not tell people as they are checking in. Since it was a busy weekend, and I had not thought about making a backup reservation somewhere, my kids and I were left to find a comfy parking spot to sleep in.
I have a longer trip coming up that included KOAs on the route, but they charge $10 a piece to cancel the reservation. I emailed and called the headquarters to get relief, but they would not waive the fees.