GW to GF
This is the United States of America. Credit cards are just fine!!
Indeed, many airfields have self fuelling installations, workable 24 hours a day (if the airfield is closed, just turn on the lights with the R/T button, land, self fuel, sod off again - the lights will turn themselves off when they feel like it).
BTW!!! Do you already have an FAA license - have you seen the new laws??