As Bill Clinton once said it depends on the meaning of it! Clearly the explanation of a true 50 amp service, i.e. 50 amp per leg, would require a 12 KW generator. You just do not find manay 12 KW generators in RV's. So if that is what the OP is looking for the answer no there is no such animal. No to what will provide adequate service would be in the order of 5 to 6 KW generator. There are generators that you can "strap together" that can come close to what the OP wants to do, and it would come down to what the OP is looking to run at any given moment. You can run two AC units from 30 amp service providing you have a power management system that would prevent both units to start up together.