Rattlesnake Mountain Primitive Campsite

It was late, we were tired and looking for a place and didn't want to pay for an overpriced RV Park when we saw this site on Campendium. We should have checked it out more carefully.
We saw "dispersed" in the description and assumed it was an area with a lot of pullouts, all free for the taking. We arrived just before sunset to find that it was just one spot at the end of the dirt road.
So we hunkered down for the night and about an hour after sunset a small car parked right along side our van (which we thought was kind of rude at the time - we never park right alongside other campers), and after a bit they knocked on the door and they were quite bothered that we were "in their campsite".
They flashed us their $10.00 receipt for the campsite and after a fair amount of confusion and apologies they agreed to let us stay parked there (they were tent camping) so we moved our van a bit up the drive to give them a bit more privacy.
The campsite is 3.7 miles down Old Maverick Road, with quite possibly the worst washboard we've driven on a gravel road in our van.
Bottom line - this site is inside the National Park, and like all primitive sites within the park, it needs to be reserved and paid for at the visitor center.
One the plus side, we had a gorgeous sunset!