RC,
The original design had 2x4 spanning the middle. When you went to the 2nd design it appears the 2x4 are still in the middle but did you add 4" pvc pipes around them? Are they full pipes or sawed in half lengthwise? If they are full pipes, how do they attach to outside frame? I see you added an inline 'T' but it seems I see the wood showing too, did you saw out the top part of the 'T' so the wood would stick out and you could screw the wood into the PVC that way? Are the legs poking through holes in the PVC now?

Thanks and wow that looks great! What is the silt plume from in the 2nd picture?