Its uncorrect that Poland was only called Poland during 1569-1795 i think it was. The Country was officialy called The Kingdom of Poland and Grand Duchy of Lithuania. So the name Poland-Lithuania would be awesome!
And maybe the Duchy og Warsaw could also be created while Napoleon is trying to conquer the world? And if its not to much to ask maybe Republic of Danzig? I would like to help or make a submod if you want to add them, that would be truly epic and add some cool changes on North Eastern Europe!