After much communication back-and-forth with My Reef Creations (passed, back-and-forth, through Southeast Aquariums), we have arrived at a final tank design. The external dimensions have not changed, but due to spacing requirements the amount of plumbing inside the overflow has been reduced. In this final design, there will be six 1.5" bulkheads in the floor of the overflow (one closed loop input, three drain lines, and two return lines), with two more 1.5" bulkheads in the front panel (to pull water from the display and feed it to the closed loop input in the floor of the overflow). Six additional 1.0" bulkheads will be located in the floor panel of the display area, for closed loop outlets.
Hopefully fabrication can begin soon on this, the most drawn-out tank build ever.