A couple of comments.
I have had my 2006 RB since 2010. I have used the microwave once, to make popcorn. I have no use for microwaves in general. So in my set-up, which sounds likes yours, my microwave serves as a cabinet for toilet paper and paper towels. It keeps the platter from bouncing around :-)
I cook with a portable propane or butane burner. Usually a single burner suffices, but on long outings (like 30 days North of the Arctic circle), a two burner is really helpful. Coleman makes several to choose from, although they are of poor reliability - I have had regulators fail ... like popcorn. I have never wanted to plumb a permanent propane system. Creating space for tanks and driving rough roads have convinced that the portable stove option works well enough. The only drawback is I wish the burner was a little lower, like at counter top height, to avoid potential fire hazard with overhanging bins, ..., etc.
I have never had problems keeping up with refrigerator draw. And my house battery is the original installed 15 years ago. I do have 250 Watts of solar panel on the penthouse. Maintaining the battery well, i.e.: avoiding deep cycling is a good design goal, and the solar cells keep the battery topped off.
I have just removed the microwave by the way. I now have a much larger bin for Toilet paper and whatever else - Hah!
2006 Sportsmobile SWB