Are you gonna sheet the wing? Might be a little flimsy with out it...

I have mine balanced about 1/2" behind the spar... Flys pretty good there. I had some .080" thick aluminum from an old sign I used for gear... I've got some .050 titanium now.... Great to know guys in the aircraft industry!! You could probably use some 1/8" x 3/4" aluminum bar stock from Home Depot. Might need to drill some lightening holes....

I attached my gear with two bolts, on that went thru the top motor mount and the other thru the bottom motor mount.