The construction of the door and frame on my 2009 19 is the same as yours. Regarding the striker plate wear, if you hold the latch lever open when closing the door you will virtually eliminate the wear on the striker plate in the future.
As for the door sealing problem, it seems to be very common for us owners of the first generation trailers with curved side walls and doors. Its probably one reason that the new trailers have straight (flat) walls and doors. The previous owner of my unit solved the seal problem by adhering self adhesive closed cell foam tape to the door (not the door gasket on the door frame) at the locations where the door does not contact the gasket when it is closed. That foam tape is available in various widths and thicknesses in most hardware stores, and has the added virtue of being cheap.