Get ready for El Nino Doug. You may be bidding good riddance to land/park hunting anyhow. Watch for the storms starting in December. If the beaches around SF erode, you could be a very busy man digging silver and such !

Oh sure, technically some are federal (those that are GGNRA). You could study the map boundaries to see where the various boundaries are. But if it were me, .... I'd be looking for that "ring my wife lost last week here".
I've heard of a guy who hunted stinson beach (yes, the federal part) for the better of a year. Because he simply didn't know any better. He did quite well just working the dry sand towel line, volleyball courts, etc... For the LIFE of him he couldn't understand why the "locals weren't all over this". Imagine his surprise when he began to meet other hobbyists, join a club, etc... and heard that it was supposedly off-limits. Odd part was: he'd been there in broad daylight for months on end. In full view of rangers, lifeguard towers, etc... Nobody had ever said so much as "boo". You can imagine his temptation to simply keep going, since it was obvious no one cared less.
So too did a friend of mine go to Ocean beach (another arm of the GGNRA boundary) to look for someone's lost ring (a legitimate search). He wondered if he needed to get "special permission", but in the end, just decided to print out the L&F ad, and just go look. He would just show it to anyone who approached him. He was never questioned or bothered.
Not saying that makes it right, but ... just sayin' !