This will only work if you leave your inverter on, you mean? Some have done that and had their battery dead the next morning. My inverter has a push button swich that cant be left on anyway, but I would be afraid to use this method if I could. Im also afraid that if I could, Id do it anyway! Actually, come to think of it... I have it on a switched line, so it wouldnt drain my battery! cool idea.
EDIT:I gotcha...only if the line is tied into the ignition.