Utah does allow for medical exemptions. I have one. But the exemption is weak. It takes the side windows down to 35% from 43%. Which in real terms does not do much. Since the combination of factory tint and the next darker level of tint after 50% takes you past that spec. In addition federal law requires that the windshield have 100% light transmission. So no exemption covers you there. Which sucks because I have to drive with sunglasses on at night. Which are way darker then tint but help with the oncoming traffic lights and green traffic lights.
In any case you are subject to the law of the state, city or municipality you are traveling in. The case is tried there and the law is according to their books. That being said they pay less attention to you with out of state plate IMHO.