CH, sounds like you had a potential great opportunity. Don't forget that tip about when a storm or rain moves in, and everyone starts to scatter, that's the perfect time for you to hit the dry's towel line, just gotta be prepared beforehand. When people are panicking and trying to move at lightning speed to get back to their cars, they're gonna be grabbing their stuff and shoving into their beach bags as fast as they can, and that's when a lot of goodies can be lost in the shuffle. Don't know why, but some people like to take their rings off and place them on their towels. In the heat of the moment, they forget the rings are on the towel, and there ya go.
Your Manti is waterproof, just make sure to take a hat & light rain jacket with hood with you. Unless lightning bolts are slamming close by, I'd try to stay as long as possible to hit the dry towel line, at least make a quick pass or two. That's the type of situation that could be a great opportunity for you, and you probably had no competition. That's one of those situations we could call being the right person, in the right place, at the right time.