There are economies of scale on external battery packs that run 12v(common wifi router DC voltage) and marine batteries also can run 12v. You could create a new power cable that never does the dc to ac conversion and use that battery pack for the wifi. Then you could run the raspberry pi or other system as the server itself.
Nice idea and don't worry about the Africa haters. Plenty of stuff is originally made for mid 20s SF techies that ends up being useful for a whole lot of other people.