Europe's RV's

DrewE wrote:
Probably the easiest would be to wire up a 50A plug converter. So long as the campground has a proper split-phase 50A socket, there is 240V between the two hot legs. The neutral line in this case would not be used. This adapter would not work with a 30A connection, even with a 30A to 50A adapter.

It might be possible, though I would not think it likely, that you may find some campgrounds where the two legs are actually two of the three phases of a 120/208 three phase supply, in which case the voltage between the legs would be 208V.

Not that easy.
US 120V comes from 2-phase 240V, while European 230V comes from 3-phase 380V.
In other words - US 240v is between hot and hot wire, while EU 230v is between hot and ground.
My limited knowledge about electricity would make me guess that resistors don't care about the phases, but anything else might.