I use an 25ft 50 amp extension cord along with my cord attached to the coach without any problems. Your wire from the breaker to the outlet should be at least be a 8/3 wire with a ground. That wire consists of 2 hot leads [black] 1 neutral [white] and a ground wire [green or could be bare] That will handle the 50 amps required to run everything. You just can't run both ACs, Microwave, TV, Coffee Pot, Electric Water heater and a blow drier all at the same time without tripping the 50 amp main.
2007 Georgetown 370TS
aka - RAYNMKR