What i did is when i drilled the hole for my Baby edge i tapped the tab for 4/40 bolts and then screwed the bolt directly into that with no washers no blind nuts. Secondly screwed the 4/40 head down into the fuse into the tab with the screw compressing the outside balsa and resting firmly on the hard wood you drilled through. clean and simple. did i also mention weight saving. Also i did drip a drop or 2 of CA in the tab to help harden the tapped threads. When you do you might need to run the tap through again to clean the threads.

Only thing you have to make sure is not to drill the hole through the fuse any bigger than the screw it self to make sure the screw head cant go threw. You end up with a 4/40 socket head screw that is flush with the out side of the plane and it will never vibrate out at least mine never did.