I want to jump in on dressing for the informal outing. I don't feel this is a good idea either. Think about how your job goes. Your success probably hinges on the ability to work with others. So what if the dressing at the informal outing backfires? You could have key people that avoid you. Will that make your job any easier?
I know we need to push for acceptance, but just shocking people with an appearance is not the correct path in my opinion. I would decide if you want to transition and handle it through HR before making it happen or keep your dressing outside of the workplace.