SeldomSeen:
I am going to recommend you check out RVParkReviews.com for the California section. Pick a starting coastal city like Oxnard, and at the top right of each page are nearby cities with RV parks listed. You should have no problems from Oxnard up to San Luis Obispo finding parks. The Central Coast from Santa Maria to San Simeon can be VERY crowded this time of year due to the heat in the Central Valley (Fresno-Bakersfield). I would research and think long and hard if I wanted to tow a 5er on Highway 1 from San Simeon (thru Big Sur) to the Monterey Penninsula. It is switchback abundant, cut into a near-vertical mountainside, 2 lane roadway, next to the ocean. If you are going North, you will be on the landward side, which is a little less nail-biting. Tour busses do traverse this road daily.
You can join US Hwy 101 at San Luis Obispo and take it as an inland route to Salinas, which is just 15 miles from the Monterey Penninsula for an alternate route.