"We have 80 MB of ATF textures of all three kinds (PVR, DXT, ETC)."
That right there is your problem. You need to reencode all your ATF Files to create a platform specific version. The PVR and DXT files don't get stripped when they're added to your final apk. In theory once you do that it should be at least half the size of what you have currently but probably around 1/3 if it's anything like DXT/PVR compression ratio (sorry not familiar with the ETC format).
Here's the command to encode a specific version per platform:
-c Create a block compressed texture set (DXT1+ETC1+PVRTC4bpp).
Use d, e or p to only encode and embed either dxt1, etc1 or pvrtc.
I'd like to add that the doc on adobe website is super unclear on this on their website. If you want the full list of options just type png2atf with no parameters, it has all the info you need.