I have been following this thread as I have been working on my Super Skybolt over the last few months. Based on what has been said about firewall integrity, I decided to beef things up. So this is what I have done: I drilled and tapped the landing gear screw holes out for 4-40 bolts instead of using the supplied machine screws. I cut a temporary access hatch into the fuselage underside. I will permanently put it back later. This cutout has allowed access to the firewall and around the landing gear. I fiberglassed around the landing gear on the inside. I traced and cut an additional firewall laminate from 3/32" birch ply. I sanded the face of the existing light ply firewall to prepare for glue. I pounded out the blind nuts, put 1"square 3/32" birch ply pieces underneath them, then reinstalled the blind nuts. I glued the firewall together and pulled the blind nuts snug, using the engine mount as a handy "clamp".

V6