Here is a link below to get you started. I will say from experience that they are inexpensive and I hate the cliche, but you get what you pay for. I know the one I stayed at in the Hualapai Mt's was full of off roaders and they partied hard until the wee hours and raced around the place all day on their quads and dirt bikes. No real patrol to speak of. I never saw a BLM Ranger around.Hope that helped a little. I favor National Parks myself. And California State Parks.
BLM manages a lot of land in CA including areas within the Mojave Desert, Lost Coast near Arcata and one of my favorite camping spots: Cache Creek management area northwest of Davis in Yolo County. Yolo County manages a campground on the creek adjacent to BLM lands which include hiking trails to some beautiful Coast Range peaks. Let me know if there is interest from this group and we can schedule a group trip. I believe Westywoman has organized a trip to this site in the past.
The Red Hills is a nice area, although we've yet to camp in that spot, only a bit of day tripping. Like Regis said, more of a spring/fall type deal b/c most BLM is at lower elevations. I'd also have to agree that NF camping is more the way to go, at least in northern CA. Nevada has a lot of BLM which is great. BLM and NF have similar camping rules, so where exactly are you looking? CA is kind of large. There are good NF spots around Sequoia/Kings Canyon and Yosemite if you're looking to see some national parks. The rest of the sierra/cascade range is also ripe with NF spots. Get yourself a Delorme Gazetter or similar, pick a backroad in the NF, and enjoy.
A personal favorite of mine is right outside of Kings Canyon called Big Meadows campground. Or at least it's in that area. As far as I can tell, it's not a real campground in the sense of paying fees, toilets and the like, but there are a few iron fire rings and picnic tables - but the best sites are down the dirt road past these things. Check the map provided by the Sequoia/Kings Canyon NP, it's near the NW entrance.
I recently drove down Silver Fork Road, near Kyburz (Hwy 50), and saw lots of camping in the El Dorado National Forest. There were at least a few bus-friendly spots but most looked like hike-in. They had markers at the entry points that kept the vehicles near the road-perhaps it's the 15' rule.
I like to go to a campground called Cottonwood in Boulevard, CA. It is in Socal off the interstate 8 in the high desert (4000ft). It cost about $6 per night and the ranger does not come around everyday.