Where the two skins meet, i left a 1/16 gap. I welded it solid, then ground it down to almost flush with a grinding wheel, then finish the edge off with a high speed sanding pad (80 grit). There will still be some pits here and there, but they can be filled with icing (which is a skim coat filler). I'm doing the main box this way,.... but on the side boxes I think I am going to use seam sealer sanded out flush. I'm still thinking on that one.
Thanks for the kudos Titanpat57, much appreciated!
I'll have some more pics tomorrow,...I forgot my camera at the shop today.