There are many RVs with fifty amp plugs that don't consume anywhere near fifty amps per leg from a 240-volt power source. My 35-foot Itasca motorhome is a good example. It has a propane range, hot water heater and furnace, In the summer I can run both air conditioners, the electric coil in my hot water heater, microwave/convection oven, TV sets and even a hair dryer and not exceed the capacity of a 240-volt two-pole 30-amp breaker and #10 wiring.
Some motorhome designs are foregoing propane and are designed to be all electric. They can quickly overload a 30-amp circuit. This past winter we camped in a friend's front driveway and plugged into his 15-amp outdoor outlet. It was sufficient to keep our batteries charged, run our furnace, TV and DVD player and brew pots of coffee.
We avoided using our microwave/convection oven and turned off the electric coil in our hot water heater because they would likely have tripped the outlet's breaker.
As long as your #10 wiring is protected with a 30-amp breaker and the connection is not so long as to cause a significant voltage drop to your RV, the simple answer to your question is, "NO."