that's kinda what I did, too. I bought an inexpensive exterior light fixture with a glass lens, then I mounted it to a scrap piece of sheet metal, then fashioned some "legs" to hold it up off the floor, painted it all flat black and just set it inside my car and ran the cord thru a slit body plug. I threw a car cover over it for a couple of years. It worked, and it gets pretty "damp" here in Seattle.
