Nice Job, I was a bit confused why you were just using 4 omnis until I read your description about adding traction wheels to the middle.
looks good we have the same braces for our gearbox. I HATE THAT BRACE.
We are using the aluminum extrusion included in the KOP to connect the two transmissions across the frame and did away with the outside bracket. It allows us to put lexan on top of the support and mount some things.