I was not talking about replacing the current Microwave with a Convection Microwave but a straight electric convection counter-top oven
IMHO the heat vented out would be WAY too much for that small enclosed area made of nothing more than pressed board.
I just replaced my micro with a store bought micro that didn't vent up and just that difference caused all kinds of problems.
An electric stove will generate a ton of heat in that enclosed microwave cabinet. It would have to be vented up and out the roof for it to be safe. Just saying.
Change out your RV oven to a convection oven would be the wiser thing to do.