The best boondocking location in the US is Gooseneck State Park in Utah near Mexico Hat. Do a Google search: it's located a few miles north of Monument Valley. (N37.17452 W109.92640) You can park as close to rim of the Canyon (as nice as Grand Canyon) as you want (?) to. Then go (take your tow vehicle) up the "Mountain" on route 261. Turn left at the first dirt road for a view from the top. (N37.23307 W109.99329) Also visit the "Garden of the Gods" at the foot of the mountain. Neither is a trip to take with any big rig: only the tow. If you have time, drive on to the Glen Canyon river. We camped here in a Motorhome.
This is a beautiful spot to dry camp if you are fully self contained. The views are amazing. There are no designated camp sites (the web page says 4, but we didn't see any), and only a couple of pit toilets. But, there is plenty of area to camp without being near anyone. You can park right at the edge of the world... if you dare! Beyond the parking lot the road contains sharp rocks, so drive with caution. There is good bicycling on the highway, at least in November when there is no traffic. The Moki Dugway and Valley of the Gods are nearby. We camped here in a Motorhome.
We used this park as a base to explore Monument Valley, Goosenecks State Park, and Natural Bridges National Monument. Not a destination park, but safe and reasonably priced. Level gravel sites, mostly pull through. Everyone else stayed just one night, on the way to somewhere else, I guess. Gas station across the road, one BBQ restaurant next door. Groceries are available at Goulding's in Monument Valley. Verizon cell on Extended Network, aircard worked, but very slow. We camped here in a Travel Trailer.
Nice park for overnight. All gravel, adequate size. Very friendly staff. Restuarant on
grounds if you don't feel like cooking. We camped here in a Motorhome.