Thanks for the tip. I looked up the kind of lights you talked about, and found some really cheap ones that fit into a car cigarette lighter and a pretty cheap transformer with the lighter fitting. I could do it for about £8-£10, I think.
If they were going to be fitted into a hood, it would be ideal, but the nano is open-topped, and if at all possible I really would like something more minimalist - the USB style of light was just perfect. I'd really appreciate hearing from anybody with any ideas on how to go about modifying it (or confirming that it can't be done) before I decide to buy the car LEDs.