Under slushy conditions and, to a lesser extent, wet roads, the rear camera almost instantly gets obscured by water droplets, making it pretty useless. I've often noticed, and exploited, the fact that turning on the rear window heater in a car without rear window wipers will greatly reduce the amount of water on the window. I think what's going on is that the viscosity of the water is reduced when it's heated, so it blows off more easily. I do use RainX on the windows, so that may be part of it. In any event, I'm pretty sure that heating the rear camera, perhaps with RainX as well, would help a lot in keeping it clear. What I'm thinking of is a heater ring that would attach to the camera lens and be fed from the rear window heater circuit.