Here is a photo of an actual rig that one of our local reefers setup.
He ended up building his rock work up around it to cleverly hide the pipework. The was a form of closed loop system he designed but in essence would work with your tank layout really. Use the middle whole on in the tank for your drain (the gray pipe, modified and raised to form a proper overflow column in the back of the tank) and surrounded with a crafted overflow shield. Then use one, two or even all four of the other holes as returns depending on how you plumb it back and just hide the pipe work in the rocks.
Here is just a quick side view sketch the overflow and drain.