Find a professional that you think you might want to work with, and be very up front and matter of fact, Tell him you are a nudist, and then offer to increase their hourly rate if he agrees to work out naked. Put the ball in his court right away, matter of fact, just like if you had any other specific requirements for someone you are hiring for contract work.
Tell them that there might be a little bit more of a homoerotic slant, but that there will be a clear limit to where you draw the line, and if you cross the line you will stop the training sessions all together. That way he can decide up front if he wants to "expand his horizons" and he won't be preoccupied with worrying that one of you will error in what your little heads might do when straining on the workout bench.
