I didn't know that was a 21st century thing.
What would you ballpark the odds are of a fairly smart guy/gal spending a few thousand dollars on books, investing some time, and passing the bar DIY-style; pretty low?
A relatively small number of folks do it, but they generally pass. That is because these folks generally do one year of law school then go on to do an apprenticeship with a lawyer in order to cover the areas that are tested. There was a recent Vermont Supreme Court Justice who was admitted this way. The big problem: the license is not really transferrable to another state because the wide majority of states (48 I think) require a J.D. to take the bar or be admitted.
That aside, a special prosecutor would be a good idea but you are correct that I don't know if there has been one before or they know what to do. There is a new AG which is good because the last one left much to be desired. The Governor is spot on: Vermont's credibility is completely shot.