I had not pondered cockpit lighting but a brief brain-storming says that a strip of LED could somehow be permanently affixed somewhere? You can get it in colors; red would be ideal for the cockpit. It is dimmable too...
My first thought was to simply glue it to the bottom of the boom, but a sail cover is going to cause problems there. A broom-handle or other straight cheap free item could be suspended under the boom, with a simple plug. I could see the apparatus being very quick to install after anchoring, and it could plug in to a simple plug with a variable resistor in-line with tthe +12V to control brightness.
Whatever you do, don't gor for blue, regardless how pretty you think it is. What color are the lights in bug zappers? ...... Trust me I know.:cussing: If you are in-land do not use blue unless you want to be considered dinner....