if you've got a reasonably high clearance vehicle, and your trailer is both small and high clearance, AND you're a buck-a-roo, head up to the top of Naciemento Fergeuson Rd near there, take a right onto South Coast Ridge Road (dirt road), go a couple miles and bear right onto the road to Prewitt Ridge, and you can dry camp anywhere around there, its national forest land... do note, road IS impassable when wet.
GPS coords:
35.9709471,-121.4527442
(Kirk Creek is down at the bottom... Prewitt Ridge is about 2200 feet elevation)