Have you insulated your tanks for winter travel?

[Eric6A]

The fresh, gray, and black tanks on my Greyhawk 24SS all have tank heaters, but no tank insulation. I think the heaters would be effective to a much lower temperature, and also use less battery power when I'm parked without AC (like overnight at a Walmart). It looks like just covering the bottom of the tank would cover most of the exposed tank, as the top appears to be up against the floor.

Has anyone insulated their tanks in any similar motorhome? How did you do it, and how much did it help?

Has anyone tried to monitor the temperature of the tank contents? An IR thermometer can easily measure the black tank, just by pointing it down the outlet with the valve open, but the other two tanks aren't accessible from inside.