I wound up completely reworking this to meet our particular requirements; Network+USB ports in back, SD card in front, HATs of varying heights on top of the PoE HAT, replacing the PoE fan with one on the front and more. I'll post the reworked Thing after the design has stabilized. In the meantime - Thanks!
Supports needed only in contact with platen, 63% overhang. Actually printed on Ender 5 Plus.