If you do what your talking about it is recommended that you cycle the battery at least once every 30 days and store it at half it's rated capacity. This means that you need to charge it, then discharge it to 9.6 volts then charge back to around the 50% mark. And putting it in the fireproof bag is fine. The only real way a li-po can flame out is if it is charge wrong or shorted out. So there really isn't much of a danger when they are just sitting.

Jason