Mounting Challenger Cargo Doors

We have three Challenger brand cargo doors to mount on our teardrop. These are a bit different from the passenger doors.
Here is what the cargo doors look like

Note there is a door seal built into the frame, with about half of the frame on the other side of the seal from the door. My first thought for mounting the doors is to drill holes and use screws in the frame on the back side of the frame, away from the door, since water would have a harder time getting into the screws. Also, I can use pan head screws and the heads won't interfere with the door. Seems like a no-brainer, right?
(However, our side walls aren't quite thick enough to mount the doors that way, unless I add some blocking. Not really a big deal.)
But, I looked for videos or other instructions on how to mount these doors, and found Challenger's instructions lacking, both in detail and accuracy. (Their instructions for these "600 Series" doors appear to be for another type altogether.) I did, however, find this video that clearly shows the screws for a cargo door on the door (and weather) side of the seal.
So, does anyone see any reason why I shouldn't mount with the screws behind the seal? Perhaps I'm missing something?
Thanks, in advance, for any thoughts.
Tom
Here is what the cargo doors look like
Note there is a door seal built into the frame, with about half of the frame on the other side of the seal from the door. My first thought for mounting the doors is to drill holes and use screws in the frame on the back side of the frame, away from the door, since water would have a harder time getting into the screws. Also, I can use pan head screws and the heads won't interfere with the door. Seems like a no-brainer, right?
(However, our side walls aren't quite thick enough to mount the doors that way, unless I add some blocking. Not really a big deal.)
But, I looked for videos or other instructions on how to mount these doors, and found Challenger's instructions lacking, both in detail and accuracy. (Their instructions for these "600 Series" doors appear to be for another type altogether.) I did, however, find this video that clearly shows the screws for a cargo door on the door (and weather) side of the seal.
So, does anyone see any reason why I shouldn't mount with the screws behind the seal? Perhaps I'm missing something?
Thanks, in advance, for any thoughts.
Tom