I know this is going to sound crazy, but have you ever thought about the MGB clown?
I have one that was originally brought back to my LFS
for injuring it's owner (nipped finger). I put him in the tank along with some jawfish and the MGB clown killed both of the jawfish. I still have the clown, he's in my new tank with a orange shoulder tang a lawnmower blenny and a 4 stripped damsel. the 4 stripe damsel only comes out at feeding unless he's at least 2 feet away from the clown, the orange shoulder tang doesn't get beaten to death because he's way faster than the clown is and the lawnmower blenny does his own thing. the clown already killed a carpenters flasher wrasse.
Anytime I put something new in the tank the clown goes and inspects it. if he doesn't like it, he knocks it over and whips it a few times with his tail. He swims toward the glass and tried to bite me when I move up to the tank to fast, and he is always rearranging the sandbed to his liking.
Maybe your clown isn't that way, but it is something to think about.
Edit: this is a picture of a feeder fish he killed and drug into his anemone about 24 hours after I took him home....... this was about a year ago