Fabbed this up today. Still have to add sheet for rigidity. I’m thinking I’ll put a 10 space fuse panel and a gad27 back there. Perhaps a remote radio and maybe a remote audio panel depending on what my panel ends up at.
The weight of the GAD27 and a remote radio isn't that much. The stock battery shelf when bolted to the lower frame is very stiff by itself. I mounted my ADHARS and the Dynon serial hub here. I built my own shelf with 0.032" sheet metal and it was 1/2 the weight of the existing stock battery plate. To make the published minimum empty weight number, you need to save every ounce of weight.
Thanks. My goal wasn’t weight savings with this, reallly it was to keep aft wiring aft and simplify a bit. And free up some panel space. I’ll have a battery there in the middle so I integrated with the tray. But you have a good point my ADAHRS could live there too. It’s on with ship power and it saves an AOA run forward. I’ll still have pitot and static going forward for a battery backed up G5.
The aft area is a great place to mount that equipment. It allows you to use short cables to the transponder and ADSB antennas. Most -8’s are nose heavy and adding weight there is usually a good thing. It’s actually easier to access for maintenance than behind the panel. I can’t tell exactly how you plan on mounting the equipment but covering up the area beside the battery limits your ability to inspect the area under the floor. Some of us added a shelf on top of the longerons.