In other words, all that adapting accomplishes nothing.
To put it another way, this isn't how electricity works.
Or... Take it Back and get a good 30A RV extension cord plus a good dogbone adapter to allow connecting 30A to a 20A receptacle. Then, minimize the electrical load in the RV. 20 should run the A/C along with the Converter and interior lighting. Won't allow microwave, coffee maker, electric water heater etc. That calls for 30A, no adapters, good connections. Even then, we have to "load shed" in summer with our 15000 A/C or winter with electric heaters. If one major load (like a toaster) goes ON, another, like Mr. Coffee, has to go OFF.
To add to Isaac's following along comment: 50A is a misnomer and 30A isn't. First the 30: One 30A hot times 120V is 3600 WATTS. Sounds like a lot but really not much to work with. Now the 50: One 50A hot times 120V is 6000 Watts and that's a big improvement over 3600 but there are TWO Hots giving 12000 WATTS to a 50A coach! That's what makes 50A Such a Big Deal! Nearly Four Times the Power over 30