Supporting troops
If we aren't going to get a way to properly trade between us, I suggest the idea of supporting troops. These would be sent to your friends city, and would appear on the action screen, like a hunt would, so you can callback when you need too.
These troops would go to your friend's city, and during an attack, they would join the battle. They would not be under the comand of the player they are defending to go attack another player, or to hunt, ect.
Like I said, I think aliances need something more to be real. Not sure if this is it but please consider it or the trade idea or atleast something.