Well for Rollback, just press ALT+F4 anytime even when you se your character is dead screen during scavenging, it will roll back to start of the day
Btw also had problems with crashing
But when you enable it on Prepare screen at night (when going to scavenge) it works flawlesly
Just press stay after you are done, even though it crashed for very 1st time I tryed it, game was saved with all duped items so it worked and starting game again and loading takes like 5s so why not
If you do not dupe more than 5 or so comodities game seems to not crash at all hovewer long do you want, you can even use it to buy full inventory from trader.
Like he have one Crowbar, you can actually buy that crowbar 12x from him (items from him disapear the moment you press trade button, but until than you can dupe them, also if you want more than you can sell him item you want to dupe
And as you have endless valuables you can trade almost everything in any quantity from him without game crashing