I suspect a number of us (confessing now..) can admit to knowing more about microwave mounting as a result of delayed learning about the "Mystery Switch" inside the cabinet over the stove... It was indeed designed and built in by Airstream to keep foolish owners from attempting to run both A/C and Microwaves simultaneously... Cleverly unlabeled, to make second and subsequent owners read their entire manuals, and then find a website like this one...
I suppose a number of microwaves have been relocated or replaced by folks who didn't learn of the Switch in time... I suspect there are some confessions of Air Conditioner replacements also by folks who's switch was in the other position, and took trailer to a non-A/S shop to have the dead A/C replaced..
There's so much to learn, and so little time... Glad it all worked out, though new combo microwave/convection oven toasters do look pretty cool...
John McG