@JenB, I think your idea is a good one.
I have my personal "in case of a hospital stay sheet" - and it is not evidence based!

It is based on (partly my) experiences. Which I think, for survival, are important and should be integrated into one's life.
Reality is reality, not science is reality. Ideally, science is the approaching process to reality. It will never be
exactly reality. It is known that most of science today doesn't do it.
We also know that it takes 15-20 years until medical scientific findings sip through to doctors, if at all.
The reality - at least in some countries - are situations like
@mango's at the dentist. Doctors shouldn't behave like that, but they mostly do. Science is not there to help - so what to do?
I had some surprises in the past with low oxygen and different drugs. Personally I didn't like these surprises so I decided to take precautions. Everybody is free to do that or not to do that. Since there are nearly no scientifical publications about which substances or situations could be problematic with ME (and since we don't know yet what the pathological process behind ME is), one is left with information from experiences. For me, this is good enough.
Very often it's not about death or life if I want an alternative drug. It's about people who have to change their routine and don't want to, it's about dominance and power ("I, the doctor, say!") and it's about money (e.g. adrenaline-free anaesthetics are more expensive and most doctors don't have them in stock and have to order them).
I don't think that MCAS and/or EDS aren't real. Reality is that, at least with MCAS - or whatever process is behind it - people get better with certain drugs (e.g. antihistamines). This is reality - there are the observations - no matter if one believes in MCAS/EDS etc or not.
There are a bunch of intelligent people behind research in MCAS or EDS. There are also not so bright ones - that's normal. More research is needed, no question, as in case of ME. What we also know from ME are different, partly contradictory hypotheses. For outstanders, ME often looks like pseudo-science, too. I never understood why MCAS/EDS/POTS etc is pseudo-science and ME is not. I think these are opinions.