Your mod is not dependent upon the Main module, yet for some reason everything within the Main module is within your mod's folders. While odd, that is the most likely reason for your >1GB size, seeing as how the normal Main.pak is >1GB in size as well.
Since it doesn't seem necessary for your mod, you should just be able to delete the Main folders from within your mod. You should be able to delete the log.txt from your mod's Story/RawFiles/ folder safely as well.
