"wborst" was the only person in this entire thread that figured out what the OP was looking for. I am looking for the same thing but can't seem to find it.
Scenario: I have a 50 amp camper. Most of the time I am camping without service and have to use a genny. The 5500 watt onboard Onan is overkill unless I want to run my AC which isn't very often. Most of the time I prefer to use my little Champion 2000 inverter genny. It is a pain in the buttocks to lug that monsterous 50amp cord that came with the camper in and out of storage. What I would prefer to do if I could find the proper adapter is use a 30 amp cord from my little portable genny and plug it into the 50 amp receptacle on the camper. None of the pig tails fit on the camper side, they only fit on the genny side.
**The key to this conversation is that we don't want to adapt a 50 amp cord to a 30 amp supply. We want to adapt a 30 amp cord to a 50 amp camper**
