For the bolt plates I normally use 1/4 inch birch ply (from the LHS) not lite ply or 3ply soft wood. The Birch ply is 5 or seven ply.

It is epoxied at the aft trailing edge area and secured to the sides of the wing saddle and the back cabin area spreader. No T nuts are used, instead using the proper pilot drill for a quarter/20 tap drill through the wing and the birch plate below. When both are drilled the 1/420 tap is used to thread the holes in the birch ply and now thin CA is dripped on the new threads. The holes are opened up in the wing to 1/4 inch or just over.

I recently compled this installation on my six engine telemaster and on a gentlemans stock senior Telemaster. For the Six Pack I choose to use double front pins and the stock big Telly I used a forward and aft bolt plates for four bolts. The single front pin will work just fine on your smaller airplane.

John