If you need to plane a lot of plank you're doing yourself a favour by using an electric planer. No need to look for a power outlet, since it runs on batteries. Just get at it!
From Data Powertools
DeWALT DCP580P2-GB 18V XR Brushless Cordless Planer Kit
Powertool World
DeWalt DCP580P2 18v XR 82mm Brushless Planer Inc 2x 5.0Ah Batts & DWV9390-XJ Dust Bag
Too expensive? Get a notification as soon as the price drops.
This product is also available at 1 unverified merchant.