i just rocked a 18 gal rubbermaid underneath and ran black tubing from the bottom of post for draining and used those green drain plugs too. Then those little black elbows on the side of one end and attached black tubing to that and that would connect to the pump. i would run 3 posts to one resi. also gromets on the plugs and elbows to seal.
The one downside to that system is not to much area for the roots to get oxygen, but in your case I see you left some empy holes so that would help with airflow.
After that i switched to aero. i made with rubbermaids and pvc and a sprinkler. now i just do soil. i like it more
i give you props for going the macgyver route. Build your own