I spent about 4 hours on the trailing edge countersinking both sides. I didn't like my drill press set up so I ended up match drilling the strip to a piece of scrap so the pilot of the CS cutter would have something to guide it. I then took a scrap piece of trailing edge strip and stuck it underneath the piece I was drilling and clecoed the whole sandwich to the scrap. I chucked the CS cage in my cordless drill and proceeded SLOWLY by cutting a little at a time constantly rechecking with a flush rivet. I read on VAF to that you should CS slightly below flush which means going deep enough to see a small ring around the flush rivet. I know the process wasn't the most efficient, but it worked.