It could be confusing for sure. Not sure how this party is going to work, often it doesn't matter much if the party is in a confined location, or on a Mod where rules can be explained. Being a Human dressed as an High-Orc for the entire event is sub-optimal for sure. Might not even be allowed per the rules, I'd have to re-read. But again, on a confined Mod type thing, all bets are off, have fun.
In the past I've seen people do masks more like Masquerade style, on that stick thing, so it's clearly a prop. Kin makeup underneath, Faerie mask on a stick with wings type deal.
On an OOG level you can do the "Clearly recognizable as <Your PC's Name>" thing. Which, while kinda lame, is effective.
You can do costumes that don't change your race. A little girl dressing up as a Doctor for Halloween is still human. So if you're a scholar dress up as a noble, or a fighter or a favorite NPC. Bonus points for dressing up as another PC and imitating them the whole time. (an idea I stole from two friends of mine that I wish I thought up)
Based on your avatar you're human, which is both a blessing and a curse in these situations. If you do change your race/obscure your face I'd stay away from PC playable races. Go super fantastical. You could even do an indestructible warrior angel.
If you can pull of costume-ception it's awesome. If I can tell that's Nette playing Avacyn who is dressed up as a dragon. That's standing ovation worthy.
Full disclosure: I am not on plot, nor in charge/associated with this party at all. Just giving some remarks from what I've seen before. If someone with more connection to the event responds, ignore me, and go with whatever they say.
All that being said, I'm guessing it'll be fine. Make a cool costume, people will roll with minor points of confusion.
Or, if I know Traverse City,
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See you all in November,
Joe