It was a close call on my trailer - locks are crappy, spinning around, and hatches are often misaligned at the "doorstep" rail. I tried to tighten it, to no avail. Flimsy door gives in, and locks remain loose. Very thin fiberglass-ish surfaces with 1/2" or 1/4" Styrofoam in between, it's compressing badly when you try and tighten it.
I recall there was not enough length of the lock barrel, to add any washers. Adding a washer probably won't help because the door is too soft, too easy to compress.
If it's safety that you're worried about - don't. These locks are ALL THE SAME, in all trailers. Ask anybody on the camp for his storage keys, and it will open your hatches.