bcbigfoot wrote:
... I have played with the idea of warping the propane tanks in a battery warmer and powering them from the 1000 watt inverter installed in the camper. ...
For tanks they do make thermostatically controlled heat blankets
A company
Power Blanket makes these for cylinders as small as 20# and 30# and have dealt with the safety issue.
Unfortunately my propane compartment is so small there is no room to fit these onto the tanks. They are pricey. Two of these are equivalent in price to the Webasto Air Top 2000 STC diesel air heater price.