I would like to see a mod that would make troops cost more upkeep or hiring when they gain more exp (chevrons) . Example , lets say i start of with a Yari Ashigaru and he gains one cheveron , so from the next turn that troop would cost me more in upkeep or if i have upgraded facilities like weaponsmith or armorer , these new troops would cost more upkeep and hiring.
These changes would reflect the better training and the better pay the veterans got in the campaign. So basically it would change similar like in MP where your veteran troops cost more money . i think a mod like this would enhance the SP feeling and realism.