You said "door trim" - do you mean some piece of decorative metal tacked onto the bay door, or the skin of the door itself? Most bay doors are a sandwich with a metal skin on the outside bonded to a metal or fiberglass door structure that provides some rigidity and a place for the handle and lock mechanism.
A picture would be a big help in getting advice on this sort of thing.
2004 American Tradition; 2014 Buick LaCRosse
Homebase in the Ocala Nat'l Forest near Ocala, FL