To clarify, this is about the permanent installation of an inverter in an inaccessible location, and it should be wired into the 120V system permanently.
So solutions like plugging the inverter into the shore power outlet don't work since, well, that's outside and can't be a permanent thing. Similarly for only plugging devices into the inverter as I need them (the inverter is not accessible).
Apparently the approach I suggested is terrible, but I don't understand then what the correct approach is. Many inverters have built-in transfer switches - what is the point of those if not to allow connected shore power to seamlessly turn off the inverter output?
I'm a bit surprised at the hostility. I asked *first* because I'm not familiar with how to do it, and this has been a generally useful forum for "howto" type questions. I understand there are significantly heightened shock and fire risks with 120, so I won't do it right. The response seems to be "if you ask about how to do X, you shouldn't do X"? That doesn't seem very enlightened.
Back to teh actual issue - most inverters, certainly those around the 1000-2000W mark offer only NEMA 5-* plugs for output, so you're pretty much stuck with NEMA 5 on one end. I suggested a NEMA 5 to NEMA 5 cable, which seems to be suicide, but what then is right way?
As I mentioned above, I do have an unused transfer switch since the coach is wired for a generator, but I don't plan to add one. So my initial thought is to use that to guard against both shore power + inverter running at the same time. Is that crazy too?