Our 2010 Fuzion 383 had a bathroom door that wouldn't latch when the 5th wheel was hitched to the truck. The door was about 1/8" from latching, and never was a problem when unhitched. I filed just enough off the inside of the latch to allow the door to stay latched when hitched. The "tongue" part is right at the very top of the strike plate when the door is closed, so it probably wouldn't have been an issue if the "tongue" had been centered on the strike plate.
Since I removed just enough material to allow the door to latch, I figure if the door starts not latching again it will mean the frame has flexed and stayed flexed. Which would not necessarily be a good thing. So far after 5 years and thousands of miles the door still latches. So I'm operating under the assumption that a little flex occurs with minimal damage.
