Yes - there was one at the Hamburger Rock campground and there was another one down the road to the north on the east side of the road - maybe 3/4 mile from the campground? It's been a few years. We camped about halfway between the two, so not super convenient, but they did exist. It was a great spot to camp and easy access to Canyonlands (and real bathrooms).

Yes, at Hamburger Rock CG and at the group sites near the Indian Creek crossing