Yes, you can camp in the parking lot of the trailhead or around it if using a tent. There is a sign asking you not to block the day use parking spaces.

When you click "get directions" here on The Dyrt and use Google Maps, you will be taken to a different free/dispersed camping area a another mile or so down the road (I camped here) first come/first served. It is made up of pullouts along a rocky two track that roughly parallels the road

In reference to the above statement. Tent campers can use either area, the only stipulation is no vehicles or generators on the other side of the fence.

In reference to #2. If you are a large RV or 5th wheel, you probably won't fit and the rest of us will have a grand time watching you get out after you discover this fact for yourself. If you're lucky you'll get the single pull-through(ish) spot that is next to the cattle gaurd.

All of the above being said. This was a great place to establish a base camp for a few days while exploring the western parts of the Organ Mountains. The pullouts vary in size, from car and tent to pickup cab style RV. Most of the spaces were occupied by #vanlife types and my bright yellow teardrop stood out. Neighbors are close enough to wave at but not intrude.