Using real life economics to win a game? That's horrible. My Mordor Army loves it!
Also try to keep your troll away from situations where his courage is tested. He's braver than the average gobbo, but that's not saying much. So, especially kill Rhadagast or Gandalf as soon as possible, because they can push your troll around like nothing.
I once fielded an Angmar ghost army against my friend's troll army (don't ask), and I won on the strength of my specters' Fell Light.