For me it just comes down to basic respect. If you want to call yourself a tuna fish sandwich, marry 3 blenders, etc, you do you and I'll call you what you want because life is too short and shitty to obsess over wishing anyone else conducted or identified themselves differently. People are who they are.
The best thing you can do is be courteous. I honestly don't really care about the story of your existential journey and why it's so important for you to be called they, and just as with most strangers and coworkers, I don't care about getting a detailed description about your sexual preferences, it just isn't that interesting to me. Tell me how you wish to be referred to, and I'll do my best to do it.
I don't understand why it's so difficult to respect other's preferences for salutation and just let everyone use the fucking bathroom. Everybody poops for fucks sake.