Too many ideas bouncing around in my head now...and they all seem to have dead ends.
Making use of some American history here. Let's say that Anakin is Beru's brother and therefore Owen is the brother-in-law. Just like would sometimes occur in the old west, Owen has been setting up a life on some outter-rim planet and has been traveling back and forth preparing to move the rest of his family out there (including Anakin). Meanwhile Anakin has been doing the"navigator on a spice freighter" thing to learn about transportation and distribution for the soon to be family farm. This family plan get blown to pieces when Anakin decides to go off to the noble cause of war (as many young men felt about WWI). Since his family is falling apart, what if Owen tries to betray Obiwan to the enemy if he and his family can get out. In the end Beru would ask Obiwan for forgiveness (Owen was only trying to protect his family) and since we are playing up the Jedi as monks, he would surely do so. Anakin would be so angry he would not talk to Owen or Beru so maybe only Obiwan knows where the Lars farm actually is. yes? no? too Lando?
OK...big jump ahead here... what about Anakin's wife.
I was thinking about the Emperor trying to kill her when she is pregnant and maybe framing the Jedi for it. Could this be the reason for his turn against the Jedi? Would his anguish overwhelm him. What if he never knew that the Jedi were actually able to save her? That's why the children were hidden.
Lastly...for tonite... Anakin's demise.
It was mentioned earlier about Obiwan mentoring a second Jedi. I kinda like this idea but I haven't got it worked out yet. There was also the statement about the rumors of Vader. I like this too, but what if we just call it "a Dark Jedi" instead...maybe simply one who kills, if we want to establish that Jedi don't kill because it would harm the force. Then we can have a big confrontation between the students that ends with anakin needing the Vader armor. The fun part is showing basically both fall to their deaths (lava, boiling oil, at this point whatever) and we glimpse the hand of one surivor. This (i know its still vague) idea would help hide Vader's identity. When we finally get the Vader vs Kenobi battle, the scripting can help cememnt the twist. Obiwan would sense who Vader is and Vader's response helps to seal the deal: Obi asks," YOU are Lord Vader?" Vader should attack him ferociously. Obi starts,"...Anakin..." Vader finally speaks, cutting him off, "is no more." The audience whould be convinced the other student survived.
Just doing some brainstorming. I don't know if any of it will be any help.