RE: Tiny magneto
As I mentioned, it isn't what you are looking for, but you could make a very light weight self sustaining system out of it. Electronic ignition, a small 4.8 volt battery pack, and the charging system to keep it charged.
I imagine the parts are expensive, but look into the Fuji and Zenoah engine ignition systems. They have a small rotor magneto such as you describe.
AV8TOR