If the rig is stored at home, I've read about some people sticking a 1500 watt Vornado space heater (an electric heater that blows -warm-, not hot air) underneath the rig to keep that section warm coupled with a 1500 watt space heater inside. There are caveats about this (such as making sure the heater underneath isn't directly on the pavement so rain doesn't hit it), but apparently some have used this with some success in lieu of winterizing.
Of course, this will come with a price on the electric bill, but I can see this being done for people who use their rig fairly often and don't want to bother winterizing/dewinterizing every time they get home.