I travel alot in an RV across a few states during the year. Im not exactly sure what the law says but I have a sneaking suspicion that it is different than a car. Since it is living quarters it is regulated different.
Same with drinking. As long as the driver isnt drinking, everyone else in the back can be. Yes. I know...we do it anyway on long trips.
Again, the law is different because the coach has living quarters.