Thanks for the detailed reply.
Actually the inside of the door is in perfect shape, outside of the corners (which you can't see from the inside. I had checked this out before buying this truck as I knew rust was a problem in these areas. Cutting off and redoing the outer skin in the corner areas would give me access to the inner part that is rusted.
The biggest reason I would like to not have to do the whole lower panel is most of the patch panels are very lightweight compared to original metal. I have done a few patch panels in the past and the quality sucks and they seem to warp much easier than the orignal steel.
I'll see if I can track down some Rust Cure. I'll at least cut out the outer corner skin and see what I am working with.