You can buy tickets in advance at this link:
https://www.sfwda.org/event-calendar#id=183&cid=1044&wid=201&type=Cal
All Camping inquiries/reservations need to go through the park directly, not Southern.
Nothing like going into the area backwards then.
Truth on water depth! Glad we didn't try to take our old 2-seat Teryx on 26's, which was the possible backup plan.