If the intent is to stay permanently, rip out anything 220 specific and replace with 110 based items. If they undersized the wiring
because 220v runs at 1/2 the amps, you may need to replace the wiring
If it's short term or you just want to sneak by, get yourself a 110v battery charger
of large amperage, and a 220v-50hz inverter
to cover your largest loads. Wire the shore power
inlet to the battery
charger and the inverter to your AC panel. You now have quality 220v-50hz power. The problem you run into is every time something fails, you have to special order it so you get the version that runs on 220v-50hz power.
(before someone says it, yes you can get away with some items using the wrong hz but generally not a great idea)