You just show up. Depending on what your rig set up is I'd suggest dropping the camper and head back. Road it bad. Bring a chair and cone then go back. It's a great place. We spent a 12 days last year and 7 this year.

As of a couple years ago, just show up. Almost no way that has changed based on the overall set up/location

This is BLM camping, its almost always First Come First Serve. This place is first come first served.