What you want is a 50A to 30A adapter like this........
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A lot of times the 30A receptacle on the CG power pedestal is worn out and/or the 30A breaker is weak from numerous tripping and/or being turned ON/OFF.
With the adapter you can plug into the 50A receptacle.
If you exceed the 30A rating of your RV Main Panel 30A breaker it will trip...........least you won't have to go outside to reset.
If you find you are tripping your main 30A breaker than you need to manage your amp draw by not using everything on electric.
Use the WH and/or fridge on propane.
It is safe to use the adapter.