My question concerns
"How can one mentally train for needing to rapidly recover from a surprise attack and the shock/pain/unreality? Can it be trained for without too much risk of injury?"
That's not the same thing as training a prearranged tactic for a specific type of attack in terms of "what the other guy does" . It just sets up a scenario to try to recreate that mental state of going into tunnel vision to try to learn how to break it as fast as possible. The idea I presented ignores what the other guy does because when you're frozen you can't analyze anyway. You'll be too slow.
It's specifically about how to handle freezing up. In that case, perhaps you do need a conditioned response, but a response to the very fact of being frozen.