You wouldn't be standing up the whole time, you'd be sitting and leaning forward on the rope.
Depending on the looseness of the rope you'd be stably leaning forward at a decent angle which will allow gravity to clear your airways.
I think it will be relatively comfortable.
I just need to figure out how to make the rope not slip so I don't end up collapsing forward if the pressure is released.
But if I can't, even if you are more tightly tied to the pole your head would still point downward.
But, yes, you're right there are alternatives indoors like a bedpost or a standing beam I guess. I just don't know if this solves the problem of aspirating your vomit into your lungs. It seems like it would probably minimize it if you're effectively standing up the whole time. But I'm not sure how scientific it is as a robust solution and preventative. This stuff all seems so risky and unknowable.
I'm not recommending you or anyone else to do this. This is just what I'm planning to do.
You're free to take inspiration if you want though.
But yeah that's the nature of all this, experimental and risky.
We have to figure all this shit out on our own and hope for the best.
I doubt there will be any scientific studies on making CTBing efficient and/or safe any time soon.