I'm not sure if this would be helpful but it is an extraordinary battery pack made in the U.S.  It is a 12V 10Ah LiFePo4 battery pack that is sealed and quite durable in the wild.  It can provide both 12V and 5V output and weighs in at about 3 lbs.  It can also be re-charged with a compatible 18V solar panel (although I'm sure other panels that can supply enough voltage would work as well) as well as a wall charger.  LiFePo4 batteries are not quite as dense as LiPo batteries but are much more stable and can be recycled thousands of times.
  (You need to Login or Register
P.S.  Regarding using a solar charger: this pack has a built-in charge controller and all kinds of charge and discharge protection.