The only time we have door fit issues is when the trailer isn’t level, or the stabilizers are out of whack. Basically- check trailer level on the door threshold and don’t crank the stabilizers down. But, sometimes what happens is the tongue jack stand, or stabilizers (stabs) or wheels will individually settle into a soft site, and cause out-of-level problems or torque the frame.
When the trailer is level and stabs are good, the door will close under it’s own weight. No slamming necessary.
Sometimes minor adjustments are necessary. Found a good how-to video for that.
See You Down the Road