Looks like Mt. Hood in the background which makes sense since the bumper stickers on the front of the Plymouth all coincide with tourist destinations along the Oregon coast.
The entire thing, from the license plate on the trailer to the design of both it and the wagon give a European feel. Also looks like it may say "London" at the beginning of a phrase on the back of the trailer's roof. Wildcard would be Australia, but the steering wheel is definitely on the left-hand side.
We used to own a '71 Shasta. It was a lot of fun. Paul used to be a Civil War reenactor. He would take to Shasta to events and sleep in it instead of the hard, cold ground. Was sad to see it go.