Shirts Poking Out From Waistcoats?

Dressing well is a sign of respect for both the people you're going to be meeting and interacting with. But you also need to respect the event itself. I like to think of this kind of it's formal stealth cosplay. You take the colors of your character and you echo them in the clothing you would wear to that event just like the Disney bound where you go to the park and say you're not actually in a Peter Pan costume but everything you're wearing is the proper colors to match what Peter Pan would wear.