How to Rebalance the scale of micromanagement?

[Galdred]

I am planning to start a Birthright campaign by first merging the kingmaker adventure path with King of the Giantdowns, and I am also working on a tactical RPG inspired by Birthright and XCOM.
But I would like both to be more centered on the party actions than the management.
As I said in this thread, I think the problem with Birthright (and one of the problem with the Gorgon alliance) is that it scales linearly with the domain size, so you start with not enough things to do (with a small domain of a single type), and end up with too much on your plate.
In order to sidestep this issue, I plan on having a detailed system to manage the player strongholds (with NPC to assign, and buildings to erect), but a very simplistic one to manage the other provinces:
So basically, a more detailed stronghold/demesne management, and less detailed province management.
I planned to have something roughly similar to Eador Genesis (only a limited number of building options in each province, and a detailed stronghold building tree).
What system would you recommend to draw inspiration from (homebrew or tabletop or from a computer game)?