So, the first idea was to type a password, to unlock a certain part of the history that would be otherwise locked. Why? Because I want to have p*rn with history and cookies, instead of private browsing without history, but I don't want it then to appear when I'm normally typing URLs in the bar, or in the history.
So, instead of changing the whole account, extensions and all; It'd be nice to have a "section locked", or "session locked" inside the account, that I open or close with a password.