Rear Access Door Panel Fix

[phlegm]

Under my rear access door, the aluminum 'rotted' and has actually torn in one section.


I don't have the time to replace the whole panel top to bottom, so I'd like to replace just the bottom 4.5" of it.

Is this possible?
Should I extend the panel below the floor or crossbrace to help with water intrusion?

I have already replaced the floor section that was back there, as it was dry rotted and I had separation, that I would like to avoid in the future.


Are there any other mods I should make to that area to reduce the chances of water intrusion?

TIA