I don't think you can identify them as single women. The married ones are easy to spot but it would require some pretty serious charm to stay with them through their D and then form a permanent relationship with them.
I'm sure they're out there but the ones with obvious signs of HD within the first couple of dates will probably have other issues that you would run from. No woman is going to advertise that she is HD except on adultfriendfinder.com. In that case, you will see them requesting girth sizes and tantric abilities to go for hours to please them. No, I think it's more easy to take a normal woman and set the expectations in the very beginning than to find someone HD. I would just look for a woman with a little bit of passion, a slight tendency to be jealous, and who doesn't seem to care about looking like the rest of the women. A non-conformist woman is a sexy woman in my book.
The problem is that to put all these variables in place, you are basically narrowing the choices down to a 1 or 2 women out of 10000 and you will need some good "game" to catch and maintain.
Anywhere is walking distance if you have the time
-Steven Wright