I added nutplates to the CIP, screwed in the sub-panels and did another trial fit of the completed panel. I needed to attach the bottom panel brackets to the side skin and went ahead and matched drill the hole through the side skin and dimpled them. This was a pretty finicky panel to install, but I really like the results. I still have to fill the pin holes in the fiberglass and drill the holes for instruments, switches, controls, etc.