My money says a trigger will eat a feather duster. If the trigger doesn't, the puffer likely will.
With that fish combination, a lot of inverts won't do, they'll end up as menu items.
As for "plants" - macroalgae (not technically a plant, but similar), there are a few sorts that aren't very palatable, but many would be picked at by the Foxface, and even the trigger.
Corals - some of the soft corals might be OK since they aren't very tasty, but the puffer and perhaps the trigger are likely to sharpen their teeth on hard corals.
Not a good idea, IMO to try going reef with those particular fish specimens.
Jenn