Another consideration, Tradewinds RV park in Vallejo. Short drive to the parking lot and take the ferry to SF (about one hour ride).
Or drive to the Richmond station and take BART to SF.
As mentioned the Alameda County fairgrounds in Pleasanton may have a bus to the Dublin BART station. The Rv park area isn't much but does have full hookups. Chabot regional park has 12 RV sites with full hookups (30 amp).