RE: Epoxy Wing Strengthening Fiber
Another way to do it...
lightly mist the cloth with 3M77 spray adhesive and apply the cloth to the center section of the wing. Then put on a latex glove and use the glove or a credit card to squeegie out medium CA glue. It takes less glue than you would expect to saturate the fibers and it is completely sandable within seconds after it "kicks".
After sanding, I use light weight spackle to feather the edges.