This part of the project is where I had the most room for improvement and took a very large portion of time mainly because of the little spaces between the plates as pictured above.
The problem I had was that I wanted the spaces to be sealed inside, so I attempted to weld a bead inside the drilled out holes. Because it was uneven and bumpy, it just ate up my 7/8in drill bits, and possibly my drill as well. Do NOT do this!!
Next time I would preferably either use one piece of metal for the clevis mounts, or four tightly stacked plates, and then coat the inside of the holes with JB Weld, to seal the very minor cracks between the four plates.
I cut the plates to the desired curve, welded them together on the outside, and then ground it down to a nice smooth finish. I chose for the hole to hang out over the lower tube, to prevent the clevis from knocking against it during normal travel.