Carl has given you some good tips, but I don't know about the spark plugs. Reminds me I've never changed the spark plugs in any of my diesel engines.
If it's the one at the harbor, the campground at Half Moon Bay is very close to the water and there's a great view of the ocean from there. It didn't look like it could accomodate many RVs though. I might have taken a photo or two while we were there (by boat), so I'll dig around in my archives.
When we lived in South Wales, there was a 40 foot tidal variation. So, if we fished from the piers, the water would be a long way down at low tide and almost lapping over the top at high tide. I also used to fish the beach. We'd go out at low tide which, because of the shallow angle of the beach, meant a long walk to the water. We'd cast into the surf and wait. That tide kept coming in, so we'd be walking back up the beach almost continually. Before long, the bait was in pretty deep water. Occasionally we'd reel in, either to bring in a fish or to "check it", then we'd restart with our line in the surf.
I must admit to never having ocean fished from a beach, pier or rocks in California, but I think Carl's warnings should be heeded.