I spent all that money and resources on troop pods intending to use them to stable my troops overnight. Now that they're at level 10 the game tells me I can't upgrade them any higher. Since those things are only good for 30 minutes each (which is ridiculously low) they can only protect for a max of 5 hours. Most people sleep longer than that.

That's not really fair. I thought all buildings could be upgraded to level 30. So I wasted the resources I would have used elsewhere. Also, how is one supposed to keep troops alive overnight?