Hey there,
I have the same situation developing in my group and I think so far all the suggestions are great.  I would like to also add, weather.  In most games, weather is just a table to roll on and used to make actions more difficult; but I think in AP, they can be used to create crisis for groups.  Unfortunately, it might be a little heavy handed of the MC, because players might not feel like they had any choice or control.  So give them some time to react.  Additionally, there is always winter, that can easily be a countdown front.  Plenty and surplus for most months out of the year, but you need to store up for a few months of basically nothing.
 
Pete