As a Zoo employee I'd like to say, that anyone who comes to the Zoo in cosplay...please, please, please be respectful!
Especially on discount Tuesdays, those are the busiest days and people have been thrown out for being too rambunctious; in groups, I might add. Honestly, just from my perspective, you'd get much more favorable treatement/fewer annoyed sighs, if you came in on a regular priced day.
I personally love seeing people come in like that! It makes me smile, and I catch sight of a handful every once in awhile, but this is just something to keep in mind. We have a lot of rabble rousers coming in as it is, so if you come in dressed up anticipate a slightly hesitant response. People will worry trouble is coming and be unsure. But that's just my two-cents! I did a zoo cosplay meet-up years ago, and it was great, so if you go have fun! Just be aware of where you are and that the staff isn't used to people coming in like that.