P.S. - If anyone does know how to properly enable / add belgian gates (like the ones in the "All Units" Mod) I would be stoked for them to help me on discord @TacoLite#7647 since I am clearly incapable of adding them on my own lol.
You can clone this tank trap:
ebps\races\german\buildings\defensive_structure\tank_trap
and then edit the blueprint to:
environment\objects\defenses\metal\belgian_gate_01\belgian_gate_01