Can I tow my trailer with Propane on ?

OK, sounds good. Now I will turn it off at gas stations, but do you pull into the gas station, then turn it off first thing, or actually stop a block away, turn it off, then pull into a gas station ?

I think for all practical purposes, it will be ok to pull into a gas station with it on, and turn it off as soon as I get out of the truck ?

Thanks for the help everyone!