Tie Down Stop Options
I placed an order for some set screws to thread into the tie down blocks from McMaster-Carr. The theory is that that set screw sits inside the tie down blocks and remains there. Then as you insert the tie down rings, they hit the set screws and will stop. This allows you to tighten down the tie down rings without crushing the skin since there is a gap between the tie down block and the skin.
I ordered a pack of the above as one option. They are 3/8″ long with a self locking patch on them. This should help them from rotating out of the tie down blocks if I choose to leave the tie down rings out of the plane until needed.
Another option was to get some smaller set screws and use two of them as jamb screws against each other to keep them from vibrating out. Both are stainless, just like the tie down rings. I have not decided which to use and when I do, I will likely offer the extras to other builders since I have many extras.