Tonight I worked toward catching the right flap with the left one. I devinyled the bottom skin, and clecoed and drilled it to the bottom of the ribs. I then fabricated shims for the aft end of the interior ribs (photo 1). Unlike the left flap, the right one required 0.025 shims behind all four ribs.
Then, using the same method as yesterday on the left flap, I drilled the hinge to the spar, lining up the edge of the gap between the barrels with the edges of the spar and skin (photo 2).