Got it installed Saturday afternoon. Did as suggested and cut 1 - 3/8" holes in the stiffener to accommodate a 3/4" deep well socket and that worked great. I should be able to find a closed grommet to put over it as a cap. For the top, instead of using flat stock, I found some old grade 8 oversized flat washers that matched the thickness of the transom cap and trimmed of an edge with a cutting wheel so that they slid over the bolt and shimmed it even with the cap. Then installed large washers like normal.