The road into the Snowbird Mesa aka Poverty Flats Boondocking is dirt and 1 miles from a paved road.
According to the "residents" of the mesa, the Bureau of Reclamation allows free lodging from October to June. I discovered only one reference on the website listed (scroll down to the Overton section). There was no maximum stay listed. There were approximately forty campers, some in boats, shelters, and trucktoppers. Water is available and there is a disposal station 10 to 15 miles down the road in Echo Bay.
The boondocking area is appropriate for all types of recreational vehicles. There are a few accessible roads, and considerable clearance is not required in the majority of locations. The ground is very stony and compact so it supports the weight of an RV no problem. You can camp comparatively close to the highway, as we did, or move deeper into the forest for more seclusion. The roads provide a great deal of separation between vehicles. Numerous campsites have rock fire rings.
Last year, while visiting the Valley of Fire State Park in southern Nevada, I noticed a boondocking location called Poverty Flats AKA Snowbird Mesa just a few miles south of the town of Overton on Highway 169. It is merely a flat, rocky location atop several plateaus, but the views of the nearby canyons, mesas, and distant mountains are spectacular. It is also conveniently located within ten minutes of Valley of Fire State Park and Lake Mead National Recreation Area's northern entrance. The town of Overton, ten minutes in the opposite direction, has grocery, hardware, and petroleum supplies. The Moapa Valley region is frequented by snowbirds and off-road enthusiasts, so the majority of your RVing needs can be met here.