four season porch sliding door for toy hauler

At the back of the hauler there should be a metal frame around the door, that should provide a fairly "movement free" zone. I would actually encourage the French door idea with a sliding/retractable screen door setup. The slider and all that glass bouncing around would worry me and you have almost the same problems with movement and settling. Also, if it was ever left unlocked during travel, the slider would slam side to side, likely with enough force to break things.

Good luck either way!