It's only possible to declare independence if one of the enabled victories has Revolution as a condition. However, if that's the case, then that victory occurs as soon as the revolution is over, even if there are other conditions. In CvTeam.cpp, under bool CvTeam::canDoRevolution() const, it checks to see if you can start a revolution. I think changing if (!bRevolution) from return false to return true would allow revolutions even without independence victory on. Tried to do this myself in RaR, since they include the dll right there, but ran into problems with visual basic right away and didn't know how to proceed. I think this change could open up more options and allow for expansion of the late game.