I'm still looking for a simple way to "save" a snapshot of my work in git, without all the ceremony of stashing etc
Not sure what you are looking for. What's wrong with stash? What ceremony are you referring to? `git stash` - `git stash pop` is as simple as it gets.
Then you can also do `git diff > changes.diff`. Or simply `rsync -avPh repo/ repo.snap/`, if your repo isn't huge. Or consider putting your repo in a filesystem that can do CoW snapshots.
What could be simpler than "$ git stash" and "$ git stash pop" ?