Question

if the rear window of your vehicle is made of covered by or treated with any material that makes the window non-transparent Florida law requires your vehicle to have

Answer 1

I believe the answer is: side mirrors on both sides.
Putting side mirrors on both sides is a form of safety precaution that allow you to see the distance between your vehicle and the vehicles behind you. (since you cannot see it from the mirrors on top of you due to the non-transparent window)

Answer 2

side mirrors on both sides