Thanks for the tutorial, Brian. I see this all the time when removing and replacing door panels. 99% of the time, the moisture shields are missing or damaged.
C.R. Laurence has a combination sealing, caulking, adhesive tape they call Wonder Tape. It is 1/2" wide , 1/16" thick and comes in 75 foot rolls. It has an adhesive on both sides, so all you do is roll it out and remove the release paper. It's overkill being 1/2" wide, but it's really easy to use.
Could one of the Body Exterior mods copy this thread to the Interior forum? I'd like to make it a sticky there. Might be a good idea to make it a sticky here too.
No one lives forever, the trick is creating something that will.