After a lot of thought, I've decided to do another custom installation: A 5" x 8" removable access plate on the left side of the fuselage (just below the NACA duct) that will give me access to the rudder pedal and fuel pump area. This will be helpful when it's time to service the fuel filter and the brake reservoirs on the pedals. The hole in the fuselage will be about 3.5" x 6.5", with a reinforcement ring and nutplates around it. The reinforcement ring will be riveted to the fuselage skin with flush rivets. I laid out some nutplates on the cut-out cover plate to see how many I'd need. Via some eyeball engineering, it looks like 20 will do.

I began by cutting out a cover plate from 0.032 sheet. This matches the thickness of the fuselage skin. The plate will be fastened to the fuselage with 20 #8 flush screws.

I also began laying out the reinforcement ring on a sheet of spare 0.040.

Finally, I ran a tap through the end of the pre-made F-839 elevator pushrod -- the one that had bad threads on one end. It works fine now.