Have you fit the dihedral brase yet?? I just started a 4* 60 last week and I found that I put a bit to much presure on the top spar at the root and I ended up with an opening for the brase that was to small. I had to cut out the spar from the first two ribs. I'm going to make a pocket for the brase usning 1/8" balse with vertical grain.

Your D tube modification looks interesting. I wish I had done that also. To late now as I have one wing pannel finished and I'm not inclined to tear it apart for the mod. Maybe I'll just make some patterns like you didn for a replacement wing.