You're not wrong. That little area btw the wrecks and the beach will be chokka block with outboards and ski boats today and tomorrow I reckon Waz. I've only been there once in a boat, on a nice Sunday, and you could hardly move. I think a weekday trip would have been much quieter!
I once rang up about using the little grass strip just off the beach to the North of the wrecks, but they wouldn't let me land there unless I was staying overnight at the resort. Someone put a light a/c into the trees at the end of the strip a few years back so it's off limits to most now. it's a 10-15 minute hop over from Caboolture, 50m walk to the beach, swim and lie on the beach, then back to Caboolture. Would make a for a nice morning jaunt.