A fellow flyer from the club commented on my build issue and it reminded me I should clarify the mount issue. So, this may help.
Thanks, Wes!
The issue is the ply firewall mounts are all laser cut with bolt mounting holes and behind that are the balsa supports.
These balsa supports cover 90% of the back of the firewall. So, you cant use wood screws.
My thought now is to cut two 1/4" plywood triangle firewall supports to replace the multiple layered balsa supports.
Then those two plywood triangle supports (cut to the correct offset) could be placed in locations that allow access to the pre-lasered bolt holes in the firewall.
Hmmmm.... That might be it.