I already made a darker than black mod. It's attached somewhere in this thread and makes the game on black difficulty VERY HARD. I didn't actually buff the stats of the Hippians, but I gave them a larger army and made them more aggressive and perhaps the most brutal I made artillery capable of destroying forts very easily, which means you really can't just hold your ground in one spot as the artillery usually get at least one shot off and once the forts defenses are down a single defeat means your entire fort of units falls. On the flip side the artillery buff exists for the player too so you can just as capably bombard them into dust, which is the only way I've been able to beat my own mod without just pumping beatrice or the wizards with bread and spamming spells.
I also have another mod, which is already available for play but is not finished, also attached in this thread. Originally it was "Romance them all", but over time I believe it's more like a "Cuck The King" kind of mod with further updates as Ares will be knocking up basically all the royalty in the kingdom with it's own ending forming the Ares empire.