I have not done it with triggers yet... but I would say give it a try. I have kept most aggressive fish in a softie reef aquarium to see exactly how much they will munch on corals, and suprisingly the corals do quite well. They get some bites taken out, but they always seem to grow it back quickly enough so that no damage ends up being done. I have yet to find anything that will touch a mushroom yet.
edit- Realize that the aggressive fish are not very large yet (largest is a 4" porky) and have been raised in the aquarium since they were all very tiny. True results can not be seen until they get to be more of a mature size, but I am still experimenting with it.