I OWN A STUDIO, FULLY EQUIPED, AND A GAL FROM OUT OF TOWN IS ASKING TO RENT THE SPACE. WHAT WOULD BE A REASONABLE PRICE PER HOUR

Well the gal won’t be able to obtain liability insurance without being certified
Therefore this is a risk to you

Whenever renting out your space I suggest:
Deposit
References
Completed application/including a copy of drivers license
Proof of Certification/insurance
The hours and expectations of said trainer

Consult with an attorney if possible

Also, I see your fitness connect page is mostly blank, are you certified?