If we're in the audience, are we looking at the front or side of the Airstream? If we're looking at the front of the trailer (directly at the propane tanks), the door will always be stage right. If we are looking at the right (curb) side of the trailer, then there are many configurations the trailers are made.
Most of the time, the door is forward of the axle. Sometimes the door is rear of the axle. The door on older Airstreams have the hinges on either the left side or right side of the door. With the correct vintage trailer, the door could swing stage left.
If you would like the door to be on the left side (street side) of the trailer, you will need to (gulp) remove the door and frame and install it on the other side. That would make me very sad, but your scene shop or prop shop could do it pretty easily. If the step needs to be moved, that is a much more difficult problem.
I assume you've seen the great photo archives of Airstreams (don't forget to donate!):
Vintage Airstream Photo Archives
This trailer might have the door you are looking for: