If you want to go it alone, you could call the 76 station just north of Sears Point. (707) 938-8133 By law, they have to give you access to air/water (if they have it) if you buy gas from them.
Personally, if you needed air I would go make a friend with another team. Someone will have brought an air compressor that can be run off their generator/garage power. This will take far less time than a RT to the gas station.
-g
Myopic Motorsport's #888 Ceci n'est pas une Citron Thunderbird ("This is not a lemon" but a 1995 tbird w/ 93 V8 swap + shopping cart rear wing + engine mounted frito maker)
2017 Sears Pointless Organizer’s Choice
Frito Making Tbird from 2018 Sears Pointless Engine Heat BBQ -
http://goo.gl/csaet4