Hmm. Never happened to me so I cannot give you any positive advice. I am on w10 too.
For the more technical oriented minds, I have noticed that the two crashes/hangs I had with Underrail so far seemed to be due to having Video Write Combining active (USWC) which, sadly, it's the default value since Windows XP. BTW having USWC makes me pretty dizzy on some games (specially some FPS like L4D2). The bad news is that you cannot disable it for testing easily since Windows Vista. The easiest way (if you want to test it out) is to use
Wagnard's DisableUSWC tool.
Add key means DISABLE USWC.
Remove key ENABLES it again.
Just reboot after enabling/disabling it.
As for savegames filesize, you can squeeze them a little using
7-zip for instance.