im also having an incredible hard time clearing e-7 myself. my biggest issue right now is also i dont have enough resources to continue to throw at the map. started out with this many resoruces
and currently have this much
so yeah this map has pissed me off beyond belief. and if i still dont manage to beat the map before the last 2 days im just gonna go to easy and finish it then. i think in my case i used all my luck when i went on easy to get harukaze. mind you that was how much reources i had after completed my capture harukaze