High-definition Waterproof Car Rear View Camera Night Vision CMOS 170 degree viewing angle
I really had planned on putting this on the inside of my cab, pointing out toward the bed.  However, now on seeing how secure and waterproof it appears to be, I will likely leave it outside mounted on my bed.  Very nice unit for the price.  Also, nice and compact and does generate a very nice picture during the day.  I don't use mine at night so I can not give you much advice on this.