Mine is a 7A with Skybolts but the concept is similar. I used .032". However, I added a strip of carbon fiber and a strip of fiberglass over it. That's about .020" thickness of stiffener material. Without the added material, I would use .025". Even if its slightly shy, the micro, primer and paint will take up the difference.
Estes Park, CO
E-mail: wirejock at yahoo dot com
Builder Blog: http://wirejockrv7a.blogspot.com
Donated 12/2022, plus a little extra.
RV-7A #73391, N511RV reserved
I cannot be, nor will I be, held responsible if you try to do the same things I do and it does not work and/or causes you loss, injury, or even death in the process.