Hi Ben,
I think the desire to add git version information to files is a hangover from earlier days when people used to do this with SCCS, CVS, RCS, and all those antique systems. With git, due to its model, that's not so commonly done nowadays.
If you want to manage your files by the complex git hash numbers, then why not check in the output to the commit as well? Then you can simply add tags to make it more humanly readable. You could add the tag name to the file name if you really so desired. Seems simpler that what you are asking to do.