Another reason front license plates are required in some states is for the "red light cameras" that are out there. It allows them to identify vehicles from multiple angles, and capture a shot of the driver's face with the front license plate so that they have a better chance in court of proving that you were the person operating the vehicle at the time. Otherwise, people who are cited for running a red light and caught by one of these cameras can make the plausible argument that it was simply another person operating their vehicle. As for a non-destructive mounting method, I'm afraid the dashboard's about your only option.