I´m having the same problem as jtsmith. The file after package process, with obb and apk together in one file, is about 81MB, but after installed in my android, turns out with 179 MB, while other big and known like the newest Final Fantasy XV mobile with only 96,18MB. My game, which has only a few images and a very simple game, has 179MB. It doesn´t make sense.
I did exactly what the link that Sean Flint recommended and other tutorials, even made the PakBlacklist and other things. But simply doesn´t work, just reducing a few MB.
And please, please, please, stop sending for other link, try to explain instead of giving a link, only if coming with an explanation.
Thanks for your attention.