Piru is fine, just small. Get there early and you will get good water. Wind comes up around 11 and it gets rough. Most people head into the ski cove and anchor for the day. If you are looking to anchor off, swim and enjoy the heat Piru works well.
I've been to Castaic a couple of times. Was a little choppy from all the boats, but has a nice cove to hang out in back in the east arm. No alcohol is allowed and speed limit is 35 mph. Both are strictly enforced.
If you want to just run your boat and not swim, Casitas in Ojai is always an option. Water is smooth almost all of the time. Bad thing about it is that body contact is not allowed. Speed limit is 40 or 45 but if you take it easy in the open area and happen to go over behind the island you should be okay. N8Dawg and I go there often.
As for Later, last I heard the boat is still there. I talked to him a couple of times and only thing I can say is he was lost, or sunk... lol. He spent more time worrying about trying to find the cheapest way to get the thing out instead of just doing it. The Sheriff Boat assisted once to try to locate it, but would not dive for it due to the depth. After they found out he was not a county resident that ended any chance of them helping again.