If you don't mind boondocking, stay at Avila Beach. You can park right on the ocean. $25 bucks a night I think. It is a beautiful place, and almost never hot. July average is 72 degrees, and a low average of 53.
http://www.portsanluis.com/
Click on "Services, Recreation, Dining". Then on "Services"...."RV Camping".
If you get there mid week you will be sure to find a PRIMO spot.