ebony "dolls" as you a put it, working at a given point. Any big metropolitan area will have a healthy  
mix of black, white, Asian, Latino girls.  Girls are constantly jumping in the business and out of it. And all it takes a Back Page ad to get started in the business...

I am writing to Bureau of Census to see if they can include this kind of information on their website, to help out "dolls" just like you....

Stay tuned..

to chat up with the locals in the cities you have under consideration, and see if you find some guys there that you think would be interested in seeing you.

That might give you an idea of how popular you would be in that city.

Next use the ad board to set a date when you'll be coming by, and offer a discount for advanced booking to that city.  (Which you already have mentioned in your site anyways.)

If the advanced bookings don't pan out to make what you need to cover expenses and your time, you can always cancell.