Ok, so I hope to drill the tank and put in the bulkheads this weekend. Here's a poor illustration of my plan.
Water will be drawn out of the tank through the blue bulkhead on the right. It will go down to the pump/canister/heater and into a PVC manifold that will allow me to distribute the flow between the red, green and yellow bulkheads. The red bulkhead will deliver water back into the submerged portion of the tank through a locline return. The yellow and green bulkheads will be connected to spraybars that will run along of the top of the back and side walls to feed the dripwalls. I'm thinking of making the spraybars out of 1/2" vinyl hose with a plug in the end and small holes poked at regular intervals along the entire length. That way I'll have a flexible spraybar that I can mold to fit the shape of my background.
The entire tank is going to be run by a powerful pressure rated pump, but ball valves on the PVC manifold will allow me to balance the flow between the 3 returns. I anticipate that most of the flow will return directly to the submerged portion through the red bulkhead and the top dripwalls will be adjusted to just be a slow trickle.
How does this sound to you guys?