make 2 90 degree bends out of some drain pipe or waste pipe and thread your wires through! you will still be able to move your wire in and out but no light will escape. or add some 4 inch ducting and let it make a S shape. simple.
I used a small box that i cut and taped around the back of my fan hole. with the cardboard i was able to make it keep out the light and allow air to get through. i know your problem is different, but you could probrallymake it work for you