I used to be a state certified vehicle inspector in RI about 25 years ago. I don't know the current laws there, but I do know that if you drive with the top up and no back window, the suction will draw your own exhaust gases into the car. With the top down, you don't have the same vacuum in that area. If I were you I would just stick a thick piece of poly on there to meet their requirements and then take your time replacing it properly.