Looking good and it appears that you are getting excellent glue joints. The extra supports are a good idea but be careful how much weight you add aft of the CG, it will all need to be balanced out and that will mean more wt up front. The aileron gap is OK as long as you don't put too much covering in the area and fill the gap. Gap could be larger and not hurt either. You'll be glad you used the wood glue when you get into the sanding, it goes so much easier.
Plywood gear reinforcement would have gone in easier if done sooner in the assy, before some of the other structure got in the way.
I'll let others advise on location/method as I have not done this mod on LT-40.

Keep up good work.