Spent a lot of time with my plexi LRU templates from steinair trying to confirm where everything will go. Was really trying to avoid having anything behind the sub-panel but it just doesn't seem possible without being quite cramped. I got on my back under the panel to see just how difficult it would be to access things - it wasn't that bad for my 46 year old self. It willl get worse I'm sure.
Ultimately elected to mount the transponder between two of the fuse ribs behind the sub-panel. Im also going to mount the GEA and IBBS on the backside of the sub-panel. That moves the fuse holder to the shelf behind the MFD. I think it is better.
With everything mostly set, I decide to go ahead and run some parachord to visualize where the wire runs will go. Still a little ways away but getting set to run wires soon.