Just to update about the crashs: they didn't happen again.
Also, I've being using Suricata 6.0.3 release since than, and no netmap issues 😸
So, I changed my RAM, and tested the old ones:
24H of MemTest86+ and at least 5hrs of GoldMemory (not the best tests, but still), resulted in not a single red flag for them (tested individually), AND I'm using them on other Win machines withouth BSOD or anything in the logs.
I already saw RAM tests failing to detect problems, so based on what you explained, I'm assuming that both 1 - the issue with Suricata's Multithreading ring access, and 2 - darkstat, were hitting some intermittent problem, that I could not with tests and other OS.