Slack afternoon, so I'll add my experiences to the list. I think you're onto something, here, willyb.
50,000 ft in a Canberra, even higher in a Victor 2 - no problem.
Last w/e up a ladder painting upstairs external windowframes - shaking like a leaf!
But here's an anomaly - one wet dinghy drill years ago, I did a wide circuit of the rescue launch suspended by the wire from a Sea King and I loved it! Doesn't seem consistent, to me. What do you think?
Late Thought: What about "wing walkers"? Do we have any of those here?