This doesn't really answer your question, but I had five second-year M. vexator seedlings in my greenhouse two winters ago and 4 of them died from the cool temperatures, the fifth was brought indoors to resuscitate in the middle of winter. But these were small seedlings, I'd guess more mature specimens would have done slightly better at least.
My greenhouse lows that winter were from upper 30s to mid-40s most nights, and the highs were only in the upper 40s to low 50s most days. So they may do better if it's mostly warm with only occasional cold snaps, rather than long periods of cool, overcast days.
The one survivor is still small but doing OK, but it comes in as a houseplant from early fall to late spring.