May have already been suggested but.........for a simple dome light I use the small "Tap" lights. They are about the size of a soda can and have 3 LED's in each for a good bit of light. They come with double sided tape on the bottom and can be stuck on any flat surface such as the inside of the poly top, upper windshield frame or even on the dash if needed. I get them in a 3 pack for $10 locally. Being LED's, batteries last seem like forever and it could'nt be any simpler install!!!