One of the drawings has two detail drawings about the overlap, one from each angle (for/aft and left/right). IIRC, we (me and Axel) beveled only the inboard skin (thats the one underneith, right?) along the side and forward edge. This allowed the overlapping skin to pull in tight along the tank and also not have a bump side to side. We used a right angle die grinder with a 2" dia sanding disc to rough it out then a medium scotchbrited disc to clean it up. The bevel tapered over a distance of about 3/4" of an inch from the full thickness of the material to about 1/4 of its thickness on the edge. We also beveled the lower, outboard edge of the wing walk doubler to smooth that transition as well.