Formed an L angle to conform to top edge of panel. Trimmed off the top flange of the panel and cleaned up the edge. Pilot drilled nutplate locations and cleco'd. Temporarily reinstalled to confirm fit. Expanded pilot holes and installed nutplates on formed L angle. Tightened screws in nutplates to attach formed L to the panel top edge, replacing the removed top flange. Installed with cleco's on the hinge. I didn't drill the top of the L to attach it to the top skin yet. I'll probably wait until ready to button up the top skin and the top skin stiffeners are in place. Still need to install an avionics shelf and avionics and that will be easier with the top skin unfastened.
The piano hinge is on the bottom side of the cabin frame bar, leaving the top available for avionics shelf support. The hinges have the pins removable at the center console point, so in addition to folding, the entire panel will be easily removed for maintenance/upgrades. The panel seems a little thin, so I may add a 2nd sheet of aluminum to it for stiffness, but I can decide on that later.
This folding panel took quite a while to do, but I'm pleased with the result. My solution was inspired by a number of others who have done similar modifications. So thanks to all who have shared their build logs, Jon Croke and the HBH videos, and Jan at Viking.