I disassembled the rest of the right flap so that I could continue dimpling the rest of the ribs and skins. I was doing as much of the dimpling using my hand squeezer, but I eventually needed my first use of the DRDT2 dimpler in order to reach some of the holes that were too far from the edge of the sheet metal.
After that I started using a scotch brite pad to scuff up all of the ribs and brackets to prepare them for eventually being primed. For the flap spar, I found that a flap disk made from scotch brite pads worked pretty well down its recessed channel.