I've Got it!
I will start a Grombrindal campaign and set an endgame Waargh crisis to trigger earlier than usual (around turn 40). That way, it is all but certain the other factions will eventually get rolled over, but there's no orc LL near Grombrindal so I'll have time to build up my forces to meet them when they arrive. Confedding the rest of the Dwarfs will be simple since they'll all probably be dead and I'll have all the grudges I will ever need!