scarlet,
You wonder if any Doms have incorporated punishment with [crucifixion]? Crucifixion by itself is punishment. It produces death through asphyxiation when the position adjustment required for exhalation becomes impossible to perform due to muscle cramps. Desperately working cramped muscles is painful.
If you go through with this, you will need both a safeword and a safe signal, preferably a passive signal such as allowing an object to drop from your grasp. You'll have to remain awake; loss of consciousness would be fatal.
The historian Josephus relates a story of discovering a friend who had been crucified. He pursuaded the guard to allow the prisoner to be taken down. The prisoner survived though not taken down until his second day. There are many who dispute the story, however, as Josephus's animus against Christianity would have motivated him to exaggerate the survivability of crucifixion.
Mr. Quirt