I don't know about more body analgesia than opiates... apples to oranges, imo; they function on two different systems (opioid peptide v endocannabinoid), and produce different states of analgesia (though, tmk, the mechanisms by which analgesia is achieved display some similarities)
But er ah uh to the OP's question- in terms of toxicity, 4 substituted tryptamines (the synthetic counterparts/precursors to naturally occurring psychedelic substances like psilocybin) are hypothesized to be very safe? As well, psychedelics are much harder to abuse than the traditional hedonic drugs; as someone with a substance abuse disorder, I find them to be the ONE thing I can avoid abusing whilst still greatly enjoying.
Used correctly, they can be fantastic for ones outlook/mental health, which, as we all know, often results in better physical health.
4-AcO-DMT (psilocetin? icr) has been a personal favorite of mine.
As well, 2C-x compounds. I'm on a very low dose of 2C-D -right now- and find it compatible with a healthy lifestyle.
Cannabis edibles are also an excellent suggestion!
Ps avoid the fuck out of rc opioids if you value your stability