Just read this on Tom Severin (gives excellent 4x instruction) pushed newsletter:
The California Superior Court of San Luis Obispo County has ruled that the California Coastal Commission does not have the authority to prohibit motorized recreational and overnight camping access at Oceano Dunes...
Just spent a couple of days in Pismo with my bride and we spent some time out on the dunes. It was really fun and never got about 68 degrees! I haven't been out on the dunes for 25 years and there are a lot of fences out there! I was able to get around the entire open area with little issue...