Options on camper washing

[TCNashville]

Hey everyone, my camper needs a good washing. Problem is my storage facility has no water. Our house is not an option, not enough room to even park it. Nearest truck stop is 52 miles away. We live in the backyard of Indiana's largest state park. I was actually thinking of renting a secluded, shady spot right next to a water spigot [$19 for one night] and giving it the once over. There would be no one else camping anywhere near me as I wash the camper. Pretty sure this is against campground rules, but only if I get caught. 5 mile round trip. Anyone have any suggestions on where to wash the camper and what do you think of my potential sneakiness.