Specifically about that third point, how long would it take to get into a “livable” range if you were free-falling? Like obviously hypoxia is a legit concern, but are you going to get out of that range quick enough to avoid real complications?

I know you said you can’t do your local box, but there’s no necessity for a static IP to do that. Dynamic DNS is relatively easy to set up, I suppose provided you have a domain name you own (which you can find for very reasonable prices).