We actually helped the theater out in costume for the premiere and were allowed in free to one of the non-sold out showings. There was a fantastic showing to help out the theater, but those outside were dressed in mainly Party City Batman masks. A few full costumes sprinkled through out.
I was very proud of this town after waking up yesterday morning. Everything went off without a hitch. People were civil, having fun and generally excited to see costumed Batman characters. All were polite.
Stating again and again, he went and GOT the riot gear. This "calling himself the Joker", seems an after thought to me. Or something the cop got out of him to create some sort of reason for all of this. Barely anyone wants to just believe he was UNSTABLE.
Until this whole thing dies down, I think the only way you'll be able to go in full costume with masks and face paint, would be to contact the theater and work with them about it. Ask to be THEIR face characters.