If you're leaving Manila, before the order to leave for Bataan, and the Decleration of her being an Open City, head up to the
Lingayen Gulf. There the Japanese invasion force landed, in force on 22DEC41 and continued to use that as their main portage until The Rock fell in MAY42. That area is target rich, and every sunk supply ship or transport is that many more supplies and soldiers that will be used against the boys you left behind. Give them as much time as you can, sink, sink, and sink some more!