RV Parks Santa Barbara, CA and Portland OR

I think you will find something. There are also the Ventura County parks just north of the town of Ventura that do not accept reservations. Busy in the summer, but if you time ir right (get there early sunday or monday). I once got into Flying Flags at the last minute in late June because I could not get into Pismo.

State CGs are indeed full, but often have last minute cancellations.