Dropping references that only someone who is trans (or at least clued into the trans community) would recognize is a good idea. One other option would be to wear a pin of some kind (transgender logo, IFGE or Tri-Ess etc.) that someone who is in the gender community would immediately recognize (adding a visual clue as well.)
And good her for going the extra mile and dressing so nicely even when she doesn't have to, sounds like my kind of lady
