So far today I have epoxied the other half of the firewall, and made the rear wing hold-down. After looking at that 1/16 TE former, I decided that it is adequate, so long as I tie my 1/4 ply firmly to the ply wing doubler. The best way, which I used to use in the past, is to use tri-stock. I glued the ply with thick CA, so I could position it with my fingers, but the tri-stock is done with titebond. Notice I left about 1/16 inset on the plate. This is to allow for the wing center F'glas tape.

I will tap the ply itself for the 1/4-20 bolts.