Some good tankmates for the more aggressive triggers are puffers, large angels, groupers, large wrasses, tangs, eels. Finding something that stays 6-8 inches could be hard.
Maybe one of the more aggressive hawkfish could work, like a arc-eye or freckled.
The Harlequin Tusk is a cool fish that doesn't get too big. One of the more aggressive clown fish could work. I would make sure to get a big one.