As Gonagn says it’s just a big open lot. Take a look at the aerial view on Google maps to get a general idea. The lot is nearly 450’ in length, about 75’ at its narrowest near the entrance and about close to 150’ across at its widest

Now that I’ve been here again, since last summer, and BLM fixed up the lot, there are 6 picnic tables - 4 that are next to the gravel lot and 2 in the grassy area, east end, for tent camping. You could fit another smaller RV next to the road when you first enter the lot (no picnic table).

No designated sites at this location. Just a large open area. Probably room for a dozen rigs if they park along the outside edges. Maybe more. Maybe the length of a football field and ~30 feet across.