Ha those usa made fj mounts were the initial inspiration for me to try find a local solution in Australia, also for cost and postage reasons.
You might have missed it in the large post….
This was what worked for me
The tie down rail is 25mm in diameter but after a quick test fit in store the 26 and even 28mm u bolts didn’t quite fit into the stow it bracket. I then found the solution in the form of Taskmaster 51 x 28.4mm 316 Stainless Steel U Bolt. Yes the 0.4mm extra made all the difference.
Remember in my case i was using a u bolt to match a specific bracket. If a full circle then 25mm (1”) is a good starting point to test
