I think that making it as module as @mixer suggests would be easier (if it’s possible), and also would allow other users to use this functionality. I’ve been brainstorming something like this for a while, ever since this thread: Renaming Conventions: Version Control System.
Could forget about GIT, and just make a module that would “save as” when triggered with -v1, -v2, etc. intelligently appended to the patch filename. That’s probably too much clutter for many, in which case perhaps the module could create a folder for the patch and keep all the versions in there. In either case, I think it would be less work than including GIT and setting up a repository. Another benefit is that the patch files would still exist normally on the users machine.