One: You probably need to get that on a medic-alert bracelet. Because in a trauma, even if it's in your pocket, nobody is going to see that until after they've cut your clothes off and are looking at shocking or intubating you.
Two: If you'd prefer death to a woman seeing your nether regions, then it's good you realize you're an "extreme case." But I think you need to consider that because of your feelings and past experience, your perceptions of interactions will also be a bit skewed. It's true for any of us that have raw nerves on a subject. You don't want staff to act crazy about your requests. You need to be the same way. I find when I'm making a bit "out there" request, being apologetic (even if not necessary) helps get the other person on my side. For example, when I make a weird diet request at a restaurant, I say up front, "I know this is weird, I'm sorry to be difficult, but can I get it [enter crazy order that evokes memories of Meg Ryan in When Harry Met Sally]?" Servers then want to get it right. (The local Chili's even has my usual order memorized and I don't even need to say all the crazy stuff anymore. Which probably means I eat there too much.) I guess this is a long way of saying, get future staff on your side rather than automatically assuming you'll be victimized, and you'll probably have more luck.