However I would add that working through a 'bad' trip or 'seriously uncomfortably weird' experience can be the exact opposite of bad. More often than not, the inability to let go or a fixation on something negative happens for a reason. (Not to say this is the case every time - sometimes hitting the panic button is the right reaction).
These drugs amplify and reveal what's happening in deep parts of the psyche - subconscious, unconscious, habits, 'ruts' we have been stuck in so long we forget they're ruts. In my experience, the most profound growth and change comes from diving headfirst into the discomfort and following it all the way down to its origin.
Source: 50+ psychedelic experiences
It's important to look at whatever happens as a learning opportunity rather than trying to push it away.
It is 100% better to be able to work through a bad trip than to take the escape hatch, but I sure wouldn't go into the experience knowing that my only option is to work through whatever happens. Knowing there's no way out might make it impossible to work through things where I would otherwise say "ok, I can go a bit further, I can always bail if I have to".
CBD oil however, is probably a good alternative. I will report back in the future with results.
You can kill a mushroom high quickly with lots of caffeine and sugar - say one red bull.
The caffeine part is particularly bad advice, as a stimulant is the last thing you want to ingest when you are already highly agitated.
A lot of people into the hippie side of psychedelic culture don't like pharmaceuticals because they're unnatural or whatever, but in practice, there's a chance that your psychedelics are going to trigger hours and hours of rolling panic attacks that feel like you're dying, to the point where you may convince yourself that you've certainly died, or perhaps that you've never been alive.
You're considering ingesting some very weird chemicals. Have Xanax on hand just in case, so you can essentially put yourself down. If you have to take it, you'll still be tripping but you simply won't care, you'll not remember much, and you'll have turned one of the possible worst PTSD-triggering experiences of your life into a "meh, that sucked" experience.
That said, you might have a great trip that opens your mind and changes your perspective on life. I'd say it's 100% worth it if you're in the right set/setting, but not worth the risk of having a terrible time without an benzodiazepine escape hatch, because things can get seriously uncomfortably weird.