With such a large tank you could consider Long Spine Urchins. I have three in my 5' tank and they are always eating. In fact the span every once and awhile. Just be mindful of those spines. I bumped into this a couple times and its not fun.
You I have a Coral Beauty that has never bothered any of my coral in a mixed reef tank. I also have a Lamarck Angel which is an open water fish and doesn't eat coral. Super reef safe.