ZBEP, you might try the "Difficulty Mod", there are several options to change neutral size and growth

Berserker, in the "Mixed Neutral" mod neutrals still have too much morale in combat. Not sure if I have an outdated version or it is still not fixed. It is no tragedy, but it makes the early game tougher.
I can make new Dif option for it. Neutrals have +1 Morale in Combat