Something to note.

In pic #5 you see balsa blocks installed over the wing retention holes. I installed those after noting that the trailing edge of the wing will deform (bend into the wing opening) as you tighten the retention screws due to the space between the wing and the mounting blocks. They're pretty easy to install. Use an appropriate thickness of balsa and drill a 10-32 hole in them. Or 1/4", either works. Glue them to the top of the mounting blocks and use the edge of the wing saddle as a guide to block sand them to the correct shape and height. A piece of masking tape applied to the saddle edges protects the covering from abrasion when sanding the blocks.