I too have 50 Amp service in my 5th wheel but do not expect to use it...so instead of schlepping around that heavy 50Amp cord, I ordered one of these: ( I try to avoid short adapters if possible)
RV Power Cord Adapter 25' 30 amp to 50 amp Marinco Locking Connector Detachable
It comes in 3 lengths (25', 36' & 50'). I opted for the 25' because for the most part, that is long enough and I already had a significant investment in 30 amp RV extension cords.
I also removed the 50Amp Marinco connnector that was attached to the cord supplied with my unit and added to a long heavy gauge 15 amp cord for use while parked/stored on the side of the house. (no 30 amp at home).
So for now I have a 25' 50amp "pigtail" stored under one of the beds which I could put into service if/when our power needs change.