Brettski, not to throw a wrench in your plans, but this would go back to a comment I made on one of your threads in the past ("do more, please").
If you look to the right and left of the ditch in either of the photos above, it looks as if you will have some pretty large areas of open water with a flat pond bottom, and what seems to be a constant depth.
For boating, I think you would be OK with any structure as long as it was 3' below the water surface.
For these broad areas of open water, I would make more of the PVC/Netting structures and make pyramids and "Stone Henge"-like structures in these areas. While this sounds daunting, I would try to put at least five structure clusters on each side of the ditch, spread out in those open areas.
For some amount of time, those PVC/Netting structures will not have the netting clogged, but eventually (and I think within a year), they will effectively be solid boxes, however, they will still be great structure and fish attactions.
