As long as it's not a wall-wart... Whoever seriously considers it a good idea to block off 2-3 outlets in a powerstrip to run one DC inverter ought to be bludgeoned with that inverter until they see reason.
Absurd as it may sound, one can find extremely short 3-prong extension cords designed specifically to take care of the wall-wart problem. Search Amazon for "1 foot extension cord" for examples.
You can even get shorter, down to a couple inches. They're fantastic.