All depends on where you are. I'd be nervous about the pants-to-the-floor thing. Most of the time, no problem. Sports bars, truck stops, etc.? You might get hassled.
I use the men's room sometimes, and depending on my pants/underwear situation, I won't want to use a urinal. Also, I need to stand to get it all out. So, I frequently close the door and stand to pee in a stall. No comments. That said... I occasionally use the men's whilst wearing skirts and dresses, and I haven't gotten comments, only mild surprise.