After installing the new gasket, our door was so hard to close that one of our granddaughters could barely manage it.
I used tin snips to cut out a white plastic shim from the bottom of a Dollar Store white plastic basket. I removed the 4 (or 6?) screws that hold the door latch mechanism to the inside of the door and installed the shim under the latch mechanism in order to move the latch a bit farther toward the inside/center of the trailer.
That made it much easier to pull the door closed enough that the latch more easily engaged the striker plate.
On the Scamp, I had to drill holes in the plastic shim for the mounting screws and 1 hole for the little "lock pin" that Scamp uses.
I hope that description was clear enough and maybe helps some.
Best of luck to you!