They won't take you. Your car doesn't meet their tech. They are strict about the two inch rule on bars.
As per their page about convertibles linked in your post:
Additionally, the car must be equipped with a 5 or 6 point harnesses and arm restraints for driver and passenger. This means you need to install a 5 or 6 point harness for you and the instructor. Arm restraints are highly recommended for you and your instructor. Finally, the roll bar must clear the occupants' helmets by 2" in a straight line from the top of the roll bar to the front fender line (which assumes that the windshield collapsed).