This is a document I decided to make after I mentioned my own practice of psychedelic meditation, and somebody asked for more details. I've been doing this for over a year now, and it has been amazing. It is worth the effort.
---update---
Based on my experience, I have found that some drugs are helpful for breath mindfulness meditation, and some are not. Although of course, all psychedelics are hard to meditate on - you have to be pretty good at meditating to master sustained focus during these experience, although doing so will deepen both your meditation and the psychedelic experience.
Helpful:
---Ayahuasca
---Mushrooms
---Caffeine (helps to be alert)
Probably helpful? Never tried:
---INSUFFLATED 5-MeO-DMT (sounds similar to ayahuasca with more emphasis on unity than visions).
---SUBLINGUAL 5-HO-DMT
Maybe helpful? Never tried:
---ibogaine (apparently the African indigenous people traditionally used it to stay still for hours without discomfort at night while hunting).
---mescaline
NOT helpful:
---vaporized DMT (getting shot out of a cannon does not help anapanasati)
---vaporized 5-MeO-DMT (getting shot out of a cannon does not help anapanasati)
---LSD (too stimulating and scattered - hard to settle down and focus. AWESOME for yoga if you can keep your shit together in a yoga class or if you know yoga well enough to do your routine though!)
---MDMA (might work for some people but for me it was too stimulating and just plagued my meditation with a sense of "this is physically bad for me" ).
---Cannabis (might work for some people, but it is simply distracting and cloudy in comparison to serotonergic psychedelics in my experience).