The inverter would be my first suggestion. You can do a test for charge times using a car... 12 volt "cigarette lighter plug" inverter to your 230 volt. I'd imagine the charge time is a bit slower than normal... not positive though.
Only other option I can think of would be some sort of "power block" that you charge from the ship one time, and lets you charge multiple batteries with its stored energy. Similar to a cellphone charge brick. I've bought one at home depot to power items on a remote shoot.