I have exactly the same problem.
I tried to turn graphics to lowest, VSync off and set MSAA samples to four. It worked the first time, and I was able to play for a few minutes. But my game crashed again while I was in there and I haven’t been able to get back in since. I tried to untick every box in the graphic settings, it doesn't work. I even have some issues to go to the entire Engwithan Digsite area, now.
You'll find my files here : https://www.dropbox.com/s/jasux226ftj3ykj/Deadfire%20Bug.rar?dl=0
Hope this helps !