Here is a somewhat messed up idea:
Why dont you drop Minsc from your party..?
The only conflict is between Minsc and Edwin and you are right, Edwin just kicks way too much a**!
I finished the game with:
Me - Archer
Keldorn
Haer'Dalis
Viconia
Imoen
Edwin
The only problem I had was with Viconia and Keldorn, (Keldorn whooped her with Carsomyr! HAHA) but I ressurected her and everything was cool after that..
But you dont have Viconia, and with you being a fighter and Keldorn being a MACHINE! you dont need the extra melee fighter.. plenty of magic, plenty of missile attacks from Aerie, Jaheira, Edwin, and Imoen (when you get her)
Just a thought..