You could use the KSE editor to raise the experience level of a brand new character and then run through peragus trying to kill the super-droids with your puny vibrobalde and T3's starting gunnery.
I'm serious. I tried that once, I can't remember my reasoning for it - but since the monsters level up with you, when I gave myself and T3 some experience, I had my arse handed to me upon entering/loading a new area. It was pretty funny really.
As to mods...I don't know of any of those - there's re-balancing mod/tweak, made by the people doing the Kotor2 Restoration project, but I don't know how much harder that makes it, if at all. Never tried it.