If you mod the nations, you can change province defense units and how often they appear. 1 unit for every 10 points of PD is possible, at least, perhaps 0 too.
You can't mod a site to give a morale bonus. You can make a site that allows the recruitment of an immobile "barkeeper" that has encumberance 10, reinvigoration -5 and casts Fanaticism renamed into Alcoholism (99 points of fatigue).
I'm not sure if you can get rid of dominion like that. You certainly can get rid of scales, though! The scales, starting pretender and even a starting prophet can be set in the .map file. Prophets can be dealth with so that they exist in a vacuum where all dominion dies and where there is no gold tobe had (pop 0, neighbourless province with a castle in it; set defenders to few skeptics with cauldrons of broth and some militia; set the owner to the nation of the prophet housed inside).
Are you going to allow buildings? Labs, temples, forts? They can't be modded yet.
This would be lots of work, and yes, it would be a total conversion. A very total conversion! However, I like it. It already sounds very good as-is. It would be interesting if the city this was set in was called Ankh-Morpork, and if one of the playable thug cartels was named City Watch.
