Interior sound deadener

Just curious - has anyone noticed any problems with moisture collecting under sound-absorbing mat and causing rust issues? I’m in the process of repairing rust issues on the floorpans of my ‘65 Dart GT convertible, and have already replaced the pans in my ‘65 coupe. It seems to me that any moisture coming up from underneath would be trapped between the mat and the floor. I’ve considered putting in something like Dynamat, but I’m not concerned about the noise or the heat, but my cars are, or will be, winter-only cars in Arizona. But even Arizona cars rust. My donor car had unexpected rust in various places and it was an Arizona car since new. Again, not criticizing, just asking a question.