For PLAN Bs most of us 30AMP Trailer guys carry a standard RV50A-30A and RV 30A-15A long (dogbone) adapters so that we can plug into either 50AMP/30AMP/20AMP service receptacles at the camp ground pedestals... I use my RV30A-15A adapter all the time to connect to my 2KW Honda generator or to an HD extension cord coming my from my house/garage 15AMP receptacle.
They also make a standard RV30A-50A long (dogbone) adapter that you can use to adapt a 30A service to a 50A RV trailer. However you will only be allowed to us up to 30AMPs of power otherwise the house circuit breakers will trip.
just my thoughts
Roy Ken
