There is almost no chance you're going to be able to keep corals, even easy ones, with that kind of bioload. I think if you want to keep a dragon in a 120 gallon aquarium you need to stick to the dragon and damsels plan.
The red coris wrasse and blue throat trigger should both be in larger than a 120 gallon tank, and I think the tusk and puffer are borderline individually, let alone when grouped with a piscivorous eel that gets pretty big.