Here are some other ideas related to the problems of recharging batteries and powering truly mobile electronics.
Once we were on our way we found that we were having difficulty supplying charged AA cells for Ju's torch. One day I realised that there was enough 'headroom' in the output voltage of the solar panel to put two NiMh AA cells in series with it and still charge the eleven AA cells in the multi-charger. Alan Watson at Porpoise built me what I needed and sent it out with some bicycle spares. The extra battery holders are for an alternate function where four AA cells are charged from the Dynohub, and don't even think about connecting those IEC sockets to the mains (they connect to the 12V solar panel)!
When all the cells are fairly flat it reduces the output current of the solar panel by as little as 15%, rising to 50% when all cells are charged.