I bought a cheapo setup from Amazon and put it into my truck. The truck has a smoked rear window--and then I put on a topper which has... another smoked piece of glass. Has to be middle of the day or someone has to have their headlights on for the rearview mirror to work--and let's face it, full sized truck has little rearward visibility as a rule. Is a nice & cheap upgrade. I did install a camera into my enclosed trailer and use that to help back up the trailer, that's a nice upgrade too.
2011 Toyota Camry, base, 2.5L/6MT, 205k, hers
2010 Toyota Tundra DC, 4.6L/6AT, 159k, ours
1999 Toyota Camry LE, 2.2L/4AT, 225k, his