This project took a backseat over the winter, in part because the outlets where we were going to bank the one fan in the barn needed to get moved, ergo the fan placement itself was still up in the air.
But! I managed to take some time today to knock out the rest of this work!
All three of the remaining units are completed and installed, and the original "pilot" unit in the big, black box (https://social.treehouse.systems/@hugo/115126863692909609) is also now moved over to the more sleek 3d-printed case.
Great success!
(only 4 fans in the summary screenshot as the 5th is a "spare" in a barn, and hidden when not powered on and available)