Nope - I don't think I've ever seen it. It just came to mind as it has been mentioned quite a lot on this forum.
It would probably suffice to have the strap/tie go through the tombstone on your design.
I've never had one come undone either - I guess rust is a sort of threadlocker as well :D
Jokes aside I try to use nylock nuts where possible and a little dap of threadlocker and/or spring washers if it's threaded eyelets.
Nope - I don't think I've ever seen it. It just came to mind as it has been mentioned quite a lot on this forum.
It would probably suffice to have the strap/tie go through the tombstone on your design.