> stewing over many hours seems like would work fine.
It won't! Good luck with it though.
But my agenda is more selfish. I like to cold-smoke meats for adding to stews, based on the knowledge that stewing in > 85'C [1] water will destroy the botulism toxin. I could just stay away from cold-smoked meats to be safe; but then I would lose out on some of the tastiest food ever :-)
It can be a confusing topic because there are 3 different things to worry about: the active bacteria, the spores, and the toxin. Of the 3, the spores are the most resistant to heat, and according to the WHO link [1] can survive multiple hours in boiling water. However the toxin seems relatively unstable.
I really need to track down their sources though.
[1] https://www.who.int/news-room/fact-sheets/detail/botulism
Although the boiling doesn't destroy the toxin itself, only the bacterial spores.
"Just cook it out" plus "your nose can tell" (it can't, spoilage microbes aren't usually illness microbes) are false beliefs that still get people killed.