There's an RV parking area along the coast between Ventura and Carpinteria near Faria Beach. These spots have one of the best views in the world outside your door.
They are literally parking spots along the Pacific Ocean. You'll need to be fully self contained, because other than porta-potties and dumpsters there are no services offered.
More info: (805) 654-3951
There are 127 spots offered along the road. Basically you pull in to a spot, find a pay station, and drop in payment. There are no reservations accepted.
To stop beach erosion, there are boulders along most of the road if not all. So you'll be rock hopping down to the water. But the area has almost always been sunny when I've been through. Sunsets are dazzling, and you'll be rocked to sleep by the sound of surf.
The park is located along the Old Rincon Highway. Recommended directions are from the Seacliff exit off of Hwy 101, but I like to take the beaches exit either just past the mission exit headed north out of Ventura and a beaches exit headed south. More details later on that.
Warning, you'll be sharing this spot with a busy roadway, a highway, and you'll be next to train tracks.