grab yourself privateers (i think) "turms your way" mod. That allows you to put your emblems anywhere on the tower.
I cant find the original mod thread but Aces has also incorporated this feature in his mod
http://www.subsim.com/radioroom/show...turms+your+way
You cant add an emblem directly to the base texture (NSS_Uboat7c_hull.tga) since it is re-used all over the tower.