I've been working on a fantasy novel, and I thought of a relevant mod concept for Medieval II. Basically, the player would work for or against the main empire of the book.

The Rakalan Empire is a mashup of the HRE and US in the sense that it's a large multiethnic conglomerate of semi-autonomous states. The central government would be the "Papal faction" and the various states of the empire would be the "catholic" faction, but the religion would work like Britannia- culture. The "conversion" from Teutonic would be secession or annexation wrt the empire, i.e. the "barbarian" kingdoms can be conquered or converted and vice versa with the existing states. I'd like to use the Kalmar Union banner change to reflect whether the state is in the empire or no, changing available units and buildings (and the banner and name) without requiring an event counter or the like, and if possible change the victory conditions as well. The latter might require a work around as I'm not entirely clear on what the banner change does (or doesn't do) with the victory conditions and other game mechanics.
All of the factions would have holding the imperial capital (Rakala) as a victory condition, but the imperial factions would be given the capital via script upon a native emperor (pope) being elected, provided all of the other victory conditions (and a few others) are met, thereby winning the game without having to suffer the wrath of the empire.
I've already drawn out a rough map for my novel which includes the states of the empire, but I need to get it into a digital form (Geomod and/or GIMP) before I can get started on everything else. If I can get the map up and running, would anyone be interested in helping out?