This kind of defeats the whole point of the game, doesn't it? I mean, from this it follows that "Ireland isn't allowed to try to unify great Britain because I rule England already," and "I'm starting as a king, so nobody is allowed to start as a count" (personally I've had more fun starting as a count in Ireland, than as a king or emperor anywhere else)
Well, my original idea was for everyone to be part of the same Kingdom/Empire and have some stability in your holdings to prevent you from being entirely dicked over. So instead of having everyone spread across the map, we'd all be together and have to vaguely cooperate to achieve some kind of goal. Like taking over the Abbasid Empire as Zunists or conquering the Roman Empire as Norse Vikings. In other words something to ease us into playing multiplayer while keeping everyone close together for maximum interaction. Yeah, you lose out on some of the freedom of choice, but managing inter-vassal relationships is suddenly way more important than in single player. You'd also never get into the problem of being unable to form X title because everyone is underneath the same liege (who could form the title and hand it out as they pleased if it wasn't an Empire).
The second game we attempt can go fully dickery though. I certainly wouldn't object to that.
Also, does ruler designer work in CK2 Ironman? I don't think it does...
It does. The game complains that the designer was used but still lets you use ironman mode. Of course you can't get achievements due to using the ruler designer so that's something to consider.
I say earliest one so we have the most time to mash potatoes turn Europe into what we want.
My idea is that we start as counts all over Europe as pagans (also Jews, Zunists, Zoroastrians) (I claim Slavic Polan because muh patriotism) and then we murder Christianity and Islam because fuck those guys, am I right? Also, Aztecs enabled because we won't proably last until 1200s but if we will some kind of external challenge would be nice.
My only problem with this is that we'll probably end up with a ton of player nations scattered about not really interacting a lot which... Kinda strikes me as silly considering that this is supposed to be a multiplayer game.