Another trial with Unity Pro

I've been building an app with regular Unity, and am currently trying to upload under 20 MB to Apple. After doing a lot of resizing of textures and changing compression settings without totally losing the integrity of the game, I'm still at 22.4 MB. Does anyone know what else I can do to get this down? Would Unity Pro help me get under this? Sadly my 30 day trial is over :( I'd like to get another trial in, so that I can evaluate it and see if it's underneath 20 MB. If it is, I will probably go ahead and buy it. What have other people done? I think the ability to stream my assets would help, too.