I agree with what Michael suggested, he has some very good points. Since the trainers are independent contractors, I would simply charge them a flat rate for rent. You also have to make sure they don’t charge less from what your in-home trainers charge, because then you are competing with them in your own gym. I see you work for Anytime Fitness. If I’m not mistaken they pay their trainers an hourly rate according to the hours they have worked, correct? The more hours they work the more they getting paid. Who does the selling in your facility?