1. Most of the quests I do, I can do from the other side of the coin.
Extortion by Deserters? I can wrangle up some unsavory men, led by a rogue of some stripe, and have them 'tax' villages I don't own. Spy Among Us? I can send a companion into a town ahead of time to help me either slip inside or degrade their ability to resist a siege. Lord/Lady Needs a Tutor? I can send my kids off to learn from some of the finest killers, scouts, healers, merchants or engineers. Artisans Can't Sell their Products in X? That's because I set a policy to make myself money. Lord Need Horses? Train Troops? Need Help With Garrison? Go get me some horses.
You get the idea.
2. Enhance the mercenary aspect.
Allow me to negotiate in more detail. I should be able to ask for an advance, for example, then haggle back and forth between money upfront and regular payouts numbers. If my party increases in size or the war begins to turn against the hiring faction? Renegotiate honorably for more money. Or simply extort the ruler (dishonorable) in exchange for not flipping sides. Special bonuses, bounties for taking lords prisoner, etc. Prohibitions in the contract -- "I will not fight Vlandia, no matter what" or "All prisoners are property of the faction, not the ransom broker" -- and similar things.
3. As a lord, balancing between notables.
We have town and village notables, artisans, merchants and gang leaders vs. headmen and landowners. Allow me, in a microsm of kingdom management, to be able to more directly influence their power compared to each other. Favoring the artisan gets me more productivity out of town. Favoring the merchants means more honorable recruits. Favoring the gang leaders gets me dishonorable recruits and underworld connections. Do I have policies that favor my villages, my castles or my towns? Each with pluses and minuses, constant tradeoffs, including favoring no one. Also allow me to use my influence to "buy them off" and keep everyone happy, but at the expense of not having as much control or power when looking outwards.