I just thought that the structure of teardrops are similar enough to get some ideas...
Hatch construction varies. Here's mine.

Did you buy it new or used??? Camp-Inn is a reputable company. I'd contact them.
As far as the door, I would pull the edge trim, and probably the aluminum sheet and seal the edges and exterior with epoxy, assuming the exterior is bare wood. I would add three coats of polyurethane finish to the interior. But that doesn't solve the root problem which is how the water is getting in.
Tony