I spent much of the day ramming my head against obscure Inform code to make inventory saving a thing.
Is it working for you?
If this works flawlessly, it could be expanded out, for instance, we could save your feats! We could save almost anything we want, since we can make a singular file for each kind of thing we want to save, avoiding the size issues. And since we're saving them to files, worrying about lumping the player with huge clunky save words also becomes a thing of the past, at least so long as you're playing at home. Not sure how the DOM keeps the files between versions.
Testing is required!