Just a related yet unrelated question.
I'm a modder, but I haven't played the full game, so I've never been past about level 9 on my characters.
What makes it too easy?
-Not enough monsters per fight?
-Monsters die before getting in range?
-Would more ranged monsters be harder?
-Would monsters a few levels above the character party help?
I could potentially make some fixes to your issues for my own mod later on.