Hello austingirl -- Welcome to the forums!
The walkaround area and countertop surfaces inside an Airstream are probably no more generous than an old style bathroom. Refrigeration is very tight. An Airstream wouldn't have much potential for keeping much food warm or being a food serving area. Serving out a window like the Hey Cupcake
on South Congress is probably a non-starter. That's a custom conversion. But who knows... It's going to be sunny on your wedding, so why not dream?
It's probably too late to find a groom with an Airstream? Cheers! Keep us informed.