-1/8" is too thin for anything bumper related
Yes and no. If I did it again, the main tube and brackets would have all been 3/16". For the side pieces and little appearance factors, 3/16's would have just add more unwanted weight.
-he cut one side of each tube in half just to clear the shackle bolt
I don't see anything wrong with this? Yes there are other ways to go about it. However, most people just use a flat strip. A box tube with a slit in it will still be MUCH stronger than just a straight flat piece of steel.
-doesnt tie into all of the holes that even factory nutstrips do
Correct. Left one out. For my application it's never been an issue.
-he used metric 8.8 bolts, which are equivalent to regular Grade 5 bolts
Acutally it's 350psi stronger than a grade 5, but yes, correct. Tractor supply didn't have metric 10.9's so I had to order them from McMaster Carr. They have since been swapped.
All in all, I did a lot of things that could/should have been done a different way, but the carrier has yet to fail me in any category. Whether it's towing, recovery, convenience, or rigidity. It all comes down to your application. My jeep is not a 6000lb fully armored rig that will be winched up 45 degree rock faces at Moab. This is my daily driver that I wanted to add a sturdy tire re-locator to. And in that aspect, it has worked perfect.
That being said, if you're building a 6000lb armored Moab monster, don't follow my thread. Except maybe the spindle idea

I still have yet to see a more captured setup.