Excellent setup!. Wish your post was up a day or two in advance. I think I would have gone with your setup.
When I checked out behind th seat as a spot, I didn't think about moving the slow moving vehicle sign back and so it didn't seem like there was enough room. Your setup solves that problem nicely!
The TB is a lot less out of the way in my setup but I think I am liking it as I tend to access it most when I am off the tractor. I think that I ought to bolt on a strip of metal at the back of the tool box to help re-inforce the fit. I'm a heck of a lot less handy than the rest of the guys here but I figure there is only one way to learn right?
Here is mine.