Welcome! I'll share my experience with you. Many years ago I had a 30 gallon fish-only up and running for quite a while with 1 small yellow tang and two small damsels. The stupid guy at the LFS sold me a 4-5" huma triggerfish saying it would be fine in my tank!!! It actually worked for about a half a year surprisingly enough - that trigger was awesome - and he and the y. tang got along nicley. But remember this is a 30 FO gallon with pathetic filtration, overstocked, and huma triggers are terribly messy eaters all this = ammonia nightmare!!! the whole tank decided to re-cycle itself, and the ammonia poisoning eventually killed every one of those fish except one three-stripe damsel who's still with me today. Can we say, devestating!!
Afterward: My 30 gal now has a yellow tang, clown and y-t damsel. The tang will soon outgrow the tank, so I'm in the process of purchasing a 75 for him that will be a FOWLR.
My conclusion: Triggers, angels, and tangs are my personal three fav types of fish, and often you can get them to get along. This would not be the problem. The size of your tank would be a problem. I know you set up the tank so you could have the trigger, but why not stick with a tang, a flame angel, and your clowns. Then Get a 60gal+ aggressive tank and there you can keep a trigger, eel, whatever else you want that's messy and aggressive. I know I'm bringing bad news, but I really hope I, and everyone else, can save you from the devestation and heartache I went through by adding a trigger to a small, overstocked tank. I really hope this helps.