Some time ago in another place and time I saw an escort who would do waxing... so while the wax was heating up....... then she would wax my back.......
I have since found that instead of waxing; there is a thing called sugaring (which I find less painful).
Personally, do the manscaping yourself, unless you cant reach. Or go to a spa to get it done. Usually escorts would rather you be clean down there before you came and see them.
Look up sugaring in your area, read thru services to find if they do men. I've seen one where they advertised "ass, back and crack "....
Also check SVIPs website, there is something about that there.