Hmm, yes, well, in an ideal world - that is, a world in which the prequels were actually well written (!!!) - I’d have a qualified agreement with you (more on that in a moment). That world doesn’t exist. The prequels as they stand are typically unliked or even loathed by a horde of Star Wars fans. If one wishes to reedit them in order to turn them into something enjoyable, one has to make do with the available material!

So, no, this reedit won’t be “impossible to pull off”; it just won’t turn out to be as substantial a story as you (and me as well) would prefer it to be. The objective here isn’t to turn the prequels into “what they should have been” - but simply to improve their watchability!

But more on the “influence character.” You’re being overly literal about it. There are all sorts of well-told stories that revolve entirely around a single character. What’s needed isn’t another character in the sense of a literal person - but simply a conflict in which the protagonist faces one or more challenges. And, well, obviously such challenges will present themselves to Obi-Wan in this reedit.

Such challenges function in the same way as what you call the “influence character,” without being literal persons.