I like the slavery rule; maybe you tweak it that you can only whip captured cities.
I think civics-wise you should be limited to:
Government: Despotism, Hereditary Rule (Emperor), or Representation
Legal: Any but Free Speech
Labor: Any but Emancipation
Economic: No State Property or Environmentalism
Religious: Any but Pacifism
Your 3 settler limitation is interesting but could cause a lot of difficulty early ... you want to Praetorian rush ASAP, but you couldn't afford the cities you capture ...
I enjoy your RP'ing. I have always had the mindset that I'm RP'ing, but I greatly enjoy your restrictions on your self.
You may only create 3 additional settlers. All additional cities must be conquered.
If you are the first to circumnavigate the globe you may build additional settlers but only settle on territories across oceans or seas (this is what the Italy should have done! This is your chance to change their history.)
You may use slavery only after you conquer your first city.
Must have culture slider set to 10% as soon as it's available for entire game.
Found at least one religion. The Holy City may not produce any war units. No barracks.
Representation or the entire game.