After working out a plan I began to plan out my work. I removed the inboard stiffiner from the shelf. Those stiffiners are .031 and I am replacing it with one .062. I had to cut the paint around the rivet heads with a Xacto knife to keep them from removing the paint from the surrounding area.
I made a stiffner out or .750 x .500 aluminum angle. Once I fitted the length and cleaned it up a bit I marked the centerline and drilled the end hole then match drilled the rest of the rivet holes from the skin to the stiffiner.
I measured out where I wanted to place nutplates and marked, drilled, countersunk them while matching them into the skin. I started to put the nutplates in the stiffiner.