I want to start a new save, but the game - for whatever stupid reason - doesn't let me have more than one save at a time, so where are the files I have to move to a different location to back up my save?

C:\Users\Username\AppData\Local\GOG.com\Galaxy\Applications\49987265717041704\Storage\Shared\Files
This save manager might be useful.
https://www.nexusmods.com/dragonsdogma/mods/40

Thanks! Also, holy shit, I miss the 90s, when your save game was just in a sub-folder in the install folder.