I carry a 50' 30A cord in my 50A DP for times when only 30A is offered. My EMS ensures I don't pull more than that in those situations. The connectors are not the same, so I carry adapters as well. In one unusual situation, I had to use both my 50A and 30A cords to reach a pedestal not very close to my RV for power in a longer site.
Jeff and Kim
2015 Fleetwood Discovery 40E
Freightliner Chassis 380HP DP
2012 Ford Escape Limited Toad