Not much trouble actually. First off tank heaters on the grey and black tank (120V/12V variety, altough I only used the 120V side). Secondly, surrounded the tanks with a loose fitting box made from reflectix. Lastly, used a 100W bulb in each area to heat the liquid in the tanks.
As for the valves, a combination of elbow heaters and trace tape took care of that issue.
I have hundeds of pictures of our winter camping setup and can easily fill in the blanks if need be. I see I have some doubters here.
Here are a few pictures (I have to dig to find the temperature reading photos less than minus 15). Oh the readings are in celcius