This happened to be the closest place to stop when I needed to rest one night on a coastal trip; as a 60-something wildlife specialist, I'm not into motocross/ATVs, and would otherwise not have stopped here. It was very convenient, however, cheap, and surprisingly interesting, so this will probably be one of go-to rest stops between LA and the Bay Area in the future.
The day use and camping areas at this park are in a long row, next to the road that brings you through this valley. They are beautifully kept, very clean and functional. Each camping area has a u-shaped RV pull-in, ramada-style shade covering a picnic table, a waist-high barbecue grill, and a fire pit. There are plenty of bathrooms in centralized small buildings all along the camping areas and beautiful, hot, private showers with sizable dressing areas.
A motocross shop sells firewood and various (non-alcoholic) beverages and munchies, as well as every kind of motorcycle gear you can imagine.
A really pleasant surprise, especially in Northern California, was its cost: a mere $10 per night/vehicle. Two vehicles can share a campsite.
When I visited in spring 2021, about half the camping spaces were inhabited. I'm not sure if there's a busier or lighter time of year.
The drawback to this park for us non-motocross types is to be surrounded by children and teenagers on motocross bikes and ATVs. From about 9:00 in the morning till about 9:00 at night, they like to zoom up and down the center campground road, and it gets pretty noisy. The first day I stopped here I was so tired I didn't much care, but stopping on my trip back I was much more rested, and the noise was much more annoying. Still, people were very friendly and pleasant and it was a pretty mellow campground, all things considered.