It occurs to me that you guys should consider contacting cottonpicker over in CPFM about a solar powered charging station.....he custom makes them to your specs, and they are designed for this type of off the grid support.
I set up remote environmental monitoring stations as part of investigations to catch polluters, etc, and a solar system means that I can charge the phone, camera, batteries, etc...as well as charge storage battery boxes for use during extended darkness/weather, etc. He made me one with two battery boxes (modular, can use 0-2 at a time) for example. These are folding units, that fold flat like a notebook when not in use, and then open up to collect sunlight when needed.
His units outperform the commercially available options I've seen, especially for the size/price ratios.
Food for thought!
And kudos to you all for your work out in the boonies!
:thumbsup::thumbsup: