This'll be fun to watch.....

I'm no engineer, let alone one expert in aeronautics... but I hack my way through...

I was thinking on your cabane adjusters...

I was thinking of a slightly different solution....

I'd use a piece of square stock on the bottom side of the upper wing. It'd be bolted to the bottom of the top wing, and the cabane would be bolted to the side of it. Then as you experiment with incidences, you could add spacers between the square stock and the wing.

If you got too many spacers for your own comfort, make new cabanes and/or square stock pieces. Heck you could even use this method to shift the wing forwards/backwards.

You're not building a supersonic fighter. It doesn't need to be uber strong. With all the wing frontal area and drag, that piece of stock isn't going to be noticable.

Just a thought.. take it for what it's worth....