When I'm driving do I run my fridge on propane or electric?

Whoops, I have to apologize. I have an Airstream and thought I was responding on the Airstream forum. This is how Airstreams are set up, as far as the 12V option. They are bringing them back on some of the smaller units.

I don't know much about other trailers but I do understand that the 12V option is more available on them. Sorry if I confused you.