I've been trying to figure out taxes. I think an 'assimilation' approach is best. I will allow High taxes maximum outside of war, Very High inside of war and/or during a state of emergency. When I take an enemy province, I must keep taxes at Very Low for 12 turns, Low for 6 turns, and finally Normal for 3 turns. After that, I may use High taxes (if I am in a state of emergency or war and want to use Very High, maybe something like 21 turns, something strict). Of course, should the enemy recapture the province within 21 turns of me taking it, the assimilation 'resets.' I figured that, aside from that limitation, should the province be recaptured within 42 turns, a special system is worked out where certain limits on taxes are applied if the enemy hold their old province for 1-4 turns, 5-10 turns, 11-15 turns and 16-21 turns (or something like that, it keeps changing).

As for limits on troop type, it will be down to tech levels of provinces. So while I may have a Citadel and Castle, I think there should possibly need to be a prevailing majority of buildings from that tech level, or my troop choices need to be based on me having 'poorer wealth.' I will figure it out, but again, I think it is best should it be based on individual provinces, not my entire empire. This will also extend to the assimilation system, in which I will have to limit myself to only certain buildings and units for so long. Might be very fun fighting with Militia Sergeants and Mounted Sergeants, etc.

Still in the process of modding my game, though, altering all those Crusades. Then I want to rebalance building cost/construction time and requirements (the Horse Farm line of buildings needs to rely on the level of Castle methinks - and I hope I don't need to change the unit requirements at the same time, although I'd hazard that I may have to...any thoughts on that?).