Headed north from San Diego there are several beach or near beach campground/RV Parks.
State Beaches:
San Onofre
Dana Point
Bolsa Chica
Crystal Cove
San Clemente
Dockweiler near LAX
Emma Woods Ventura
Private:
Oceanside
Newport Dunes
Malibu RV Park on east side of PCH
Ventura RV Resort
County of Ventura:
Rincon Parkway... first come first to get a site. Best way to get a site is to show up Monday through Wednesday in the morning. Thursday thru Sunday tough to get a site.
Also Faria and Hobson but tough to get a big rig in
Several State beach campgrounds in Santa Barbara and San Luis Obispo areas
