Insane Difficulty: How to up the difficulty for Front Mission 3?? - Insane Difficulty

I am a fan of Front Mission 3 and I want to up the difficulty of this pretty easy game.
I am not fond of self imposed limits. There's only me and the computer and neither of us care for that kind of shenanigans.
However, I want to make the game harder a bit and here we are.

Stage One: identify the places where we can make the game harder.

Money and loots are pretty much coded already, changes are not explainable.
Can we somehow change the level and skills or HP of the enemy units appear in the battlefield?

I'm not sure I understand the question. Have you done all platinum medals playing simulators no more than once each? When I go through the game, I don't buy wanzer parts except maybe a second Zenislev body for a melee focused unit and make do with captured wanzers. This is merely my personal playing style and could be called a self-imposed limitation though.

Without editing tools or self-imposed limitations though, little comes to mind. One thing to do is place your units in the least advantageous order since the AI tends to favor attacking the unit placed first.