Ok, I have the same problem almost. My game isn't done, but the assets are kicking over the 50mb point and when the game is dnoe will likely hit 100.
I can't give you a %100 how too, however I did bring this point up with Ashley and he did make a suggestion. Just know that I cannot validate any of this.
0. Your game even when exported through android needs to run off a server
(this is the part i'm not %100 about, get Ashley to clarify)
1. Export your for what ever android style you want.
2. strip the assets out
3. put your assets onto the server that hosts the game.
4. Let players know that there are assets to download
5. The game should download the assets from the host only once(unless there is an update)
There is suppose to be a way to handle large games. But here is my suggestion. emai Scirra/Ashley directory and get his help. Since it seems no one else has done this yet, no one has gotten the clarification to do this.
Personally I would rather have extenion APK so that I can make expansions.