https://rvshare.com/
This place does RV rentals. I did a search for driveable RV's within 15 miles of Oakland and came up with a lot of options. Prices were from about $225/night to over $400 a night. Figure, pick up Friday night and drive to the GGYC. Return on Sunday morning...two nights, probably $450 - $500 for an RV with an inside table to tot up finishers and get out of the wind.
I'm not sure if the City of San Francisco allows overnight parking by the GGYC, though.
1968 Selmer Series 9 B-flat and A clarinets
1962 Buesher "Aristocrat" tenor saxophone
Piper One Design 24, Hull #35; "Alpha"