My 2 cents:
You know that "Peel & Seal" stuff they sell at Home Depot? I used it on my step side fenders & roll pan as welting when I put the bed back together. It is soft aluminum faced, self sticking and cuts easily.
Might be something you'd like to try. Check out post #105 here for some photos:
http://talk.classicparts.com/showthread.php?t=13928&page=7Hope that helps.

John