There is so much open desert in that area folks can camp pretty much anywhere. Camping right at the gate might be fun though. It's towards the end of the summer rains, so there is the possibility of some heavy thunderstorms in the area. I've been up there when the road washed out between Rachel and the 93-375 junction. Hours of fun right there.
The real issue for folks going up there is local logistics. Last time I was there, Rachel had no grocery store or gas station. The only "restaurant" is the Little A'Le'Inn which has a dozen or so tables. Even if a couple of thousand folks show up to watch the festivities and assuming they can get food, water, and fuel, they might have a bit of an issue. There is fuel and a grocery store is in Alamo, about 50 miles south. There is a gas station a few miles closer in Ash Springs. Still a 45 mile drive.
Please be prepared if you or anyone else you know, is heading up there.
Abby