How close is the nearest super market?

There are markets on and off site...12 minutes for off site. Salvane, CA is 15-20 minutes away.

Yes other than the campground store, there is a store in santa ynez that is probably the easiest to get to. Maybe half an hour or a little bit less. Nice store though.

There is a market at the campground, along with a gas station. Outside of that, there's Santa Barbara to the south, and Santa Ynez to the north. Either way, about half an hour. By the way, the market is closed on Mondays.

There is a little store on site that has a bit of everything. Aside from that, I think it was 25 to 30 min away as I recall.