In changing out the door handle/lock on my 2017 Scamp, I discovered another area that would eventually cause damage to the trailer. The old lock did not have a gasket or any sealant around the perimeter. When I removed it there is a hole about 1" diameter thru the fiberglass and into the plywood backing. The wood was wet and soft which means that water has been getting into it. I would expect this to eventually cause damage to the bottom of the door.
In this case I cleaned the soft wood out, let it dry and sealed it as best I could with polyurethane. Most importantly I added a bead of butyl rubber around the handle/lock when I put it back. Hopefully that takes care of the problem, especially since you can't actually see any problem without really looking.
By the way, I replaced the handle/lock after I read here that almost all trailers use the very same #112 key. I got a replacement from Bauer that is NOT #112. Not really been a problem as nobody has ever messed with our Scamp, but I take the Boy Scout motto, Be Prepared, to heart. I also tend to over-engineer things, so this makes me "feel good".
Since you know water got into the door you may want to drill two drain holes into the bottom inside of the door where filler is glassed. I have worked on several Scamps where the doors had trapped and filled with water. When that happens, it rots the core and you have a fairly major project.
Eddie