"If anime is strictly not allowed or completely unrelatable and frowned on by the audience then maybe choose something else that they will approve of like Vampires from Ann Rice or Elves from Lord of the Rings or whatever"

I know you're supposing since you have never actually been to a Costume Con, but as ladyofthethread alredy knows Anime is most certainly allowed and welcome at Costume Con. (I'm posting this for those who might be reading this thread so they don't get some wierd idea that it isn't.)

Several of the award winning costumes from this past costume con for example were from anime/manga/japanese culture sources: http://www.costume-con.com/cc27/winners.html

Furthermore the Sci-Fi Fantasy masquerade director herself has been a Cosplay masquerade director in the past.