Lantley, what does that plug accomplish exactly? look like it is just a exterior mounted male plug that has a female extension cord on it
You could get a 240 plug pigtail that seperates into two phases, run your camper 120 volt on one phase, and the heater on another phase by using the extension cord you mentioned.
Or, as mentioned, just turn off heater when you run microwave.
NASA spent huge amounts of money inventing a ball point pen that will write in the zero-gravity of outer space. Russia just uses pencils. Don't over-think stuff.
