Not sure what you mean by unload -all.
"unload -all" is a command that you would need to run in the DFHack console (it's a separate window that should open at the same time as DF - if it doesn't, it may be disabled in the PyLNP launcher).
Note that if you're accustomed to having DFHack plugins available, I wouldn't recommend playing in this state - just run the game long enough to get an idea of whether the crashes are still occurring.
I remember DFHack used to have a save and keep playing that was considered buggy
That would be "quicksave", another command (see above). By default, you can also run it by pressing Ctrl-Alt-S on the main fortress mode screen. I don't recall it being considered buggy, but it should be stable now (it just triggers DF's native autosave feature).
Are there any kind of crashlogs hidden outside the main directory to look at? So far I've found nothing to give me even a clue what is happening.
Likely not in this case. Generally, being able to log useful information about a crash requires knowing enough about the crash that it would be preventable anyway.
If it is reproducible in a short amount of time with a specific save, uploading the save to
https://dffd.bay12games.com/ could help others diagnose the issue.