Well what if the 50 is not working but the 30 is OK? If you really want to be prepared to use whatever is on the pedestal (for 120 VAC no more than 15 amps) then get both of these...
https://www.amazon.com/Camco-PowerGrip-Durable-Electrical-Adapter/dp/B00192QB3I
(the 30M/15F one) and also get
https://www.amazon.com/Adapter-Heavy-Durable-Easier-Indicator/dp/B07X44ZYYQ

But it will be a waste of money I am sure... I got a 50 to 30 adapter for my RV.... never needed it.