I don't believe there is any boondocking allowed anywhere on the Navajo Reservation and certainly not within the park itself. As a previous poster mentioned Valley of the Gods, Goosenecks State Park, If you are willing to drive up the Moki Dugway (which you may or may not be able to do depending on your rig and setup) there is a lot of it up there. Muley Point which is right on the edge of the mesa top, the road to it is decent until you get close to the point then it gets rougher but have seen some good size fifth wheels up there though I doubt they went up the dugway more than likely came in from the north though maybe.