Embarked on the modification to make the floorboard removable. I carefully reviewed each rivet hole that attaches the floorboards to make sure which ones will get nutplates and which ones won't - some rivet holes are in locations that would make installing a nutplate very difficult. Then I drilled the #19 holes in the floorboard and fuselage under floor structure for #8 screws. I then began drilling the nutplate holes using my #8 nutplate jig. I got through most of them before I ran out of time and had to go to work.
Here's the understructure that was drilled out to accept #8 screws to attach the floorboard.
Drilling nutplate rivet holes using the #8 nutplate jig.
Doing the same thing but now I'm employing the right angle drill attachement due to access