I believe that unless the author has major political abilities, of which they can convey to the audience well, Lelouch must convince the Black Knights to 'destroy' Britannia because Britannia will never let the Sakuradite go. Not when all modern technology depends on it. And Japan is weaker than when they were invaded with less of the political standing.
If the tried to instigate revolutions, the only places worth the little time, which he does not have enough of, are the Chinese Federation & the Euro Universe. He needs a military. It's all well & good to incite the civilians, but I don't think Charles will care. Do they even have Geneva Conventions? It doesn't help that Japan has most of the Sakuradite. He needs to secure Japan to so the rebels don't die in droves. Everywhere else is essentially meaningless.
He might not like a SAZ because it's a false peace. Expedient, but false. Especially when you cross the city lines. I would imagine he would avoid all the people he doesn't want killed though. It will not be a safe venture for sure. Not with the Geass Order & especially if he knows that Charles knows anything or has a Geass.
He can't banboozle his father because as R2 showed, he was banboozled -by- his father. Judging from the flashback, his geass wasn't disabled; he was held down by Suzaku. It's certainly going to be suspenseful, as you mentioned later. The main issue, either during or after, is that he doesn't know about Rolo, which by how R2 went, means that he will die.
The problem with that, in my view, is that he's had enough experience with that. He does it himself, he knows Suzaku, (depending on when he's sent back) he's seen the Black Knight's Betrayal, he knows about Marianne, Charles, Schneizel, Anya.... If anything, it should make him even more paranoid. Especially with Charles' ability to rewrite memories or Marianne's ability to take over bodies. He's an information buff - I think he would not take things for granted. The issue is trust, & I don't like the stories where he starts tossing it around freely.
It comes to me that if he knows it was time-travel, I hope he reads up on the theories. Your idea is based on him assuming, or beginning to assume, it's one kind, but if he reads up on the varying ideas, I would hope Lelouch starts all his relationships over from scratch save some kind of vetting process & note the ones that would be least susceptible to change.