Simplest option, as mentioned above, is to turn off the main lights an hour (huuuuge safety margin) before you will be developing then just use a desk-lamp (with tungsten, led or halogen bulb) for the time remaining. Even an led bike light would make enough illumination to set up your developing trays, if not already done earlier under your main lighting. Basically there is no need to solve the problem when you can avoid it with no effort or cost.