there is an extended stay america hotel right after you get over the bay bridge. the location looks really sketchy but they have a pretty secure parking lot and beds. i booked a last minute (on the border of sleeping in a car last minute) hotel for 80$. no bugs or bedbugs when i stayed but i have read reviews claiming otherwise.
i'm sure that their rates will go up because of the weekend, but it is worth a shot if you don't mind the 15 minute drive to the park.