how about rumours of a darth vader, like transmitions intercepted by the jedi. it would be an almost watchmen like reveal, when anakin thinks he has discovered darth vader (ie approaching palpy at his confession) palpatine could uncover "no anakin, YOU are darth vader", like anakin has already begun to fall by that point. events could follow on in a similar fashion. maybe anakin disappears for a while, to add mystery.

i guess it all comes down to whether anakin is revealed as darth vader. if not anakin could talk about vader in 3rd person all the time.