Maybe I missed something. Someone help me out here.
If you are using an adapter plugged into the 50A service then plugging in your 30A cord to this setup you have lost the protection of the 30A circuit breaker. In this arrangement your cord is not protected form a over current situation. I understand that the internal wiring in the camper is protected by the 30A breaker in the camper but the service cord between the camper and the adapter is NOT protected. There is a reason we have these components sized and matched to their usage. Sounds like NEC is be disregarded here. I'm not asking CAN it work I asking SHOULD it be used.