A page is not auto-saved until it is "Created". Once we have created a document then we have an ID to which we can refer and save edit in an AJAXY way without having to push button (other than your keyboard typing to trigger autosave every so often).
How about auto-saving a document pre clicking of the "create" button?
Do we want to save the pre-create edits in a 'tmp' collection? Say the moment you got $x amount of characters, we start saving that shiite.