How to keep propane from freezing

i would talk to the local propane supplier about another tank hooked into your system save the built in tank for when that one runs out then you can call them to come fill it up at least a 100 pound tank or you will be hauling propane a lot. forget the 20 pound cylinders they would only last a few days if it gets below zero. i used one of my trailers for snowmobiling in wisconsin. survived a 38 below zero night on propane had one of the lay down propane tanks by the trailer. i used the 3m window insulator kits to do the windows inside and outside to stop the drafts. it worked out well. you could use some electric heat to supplement your heater but keep it up away from the dogs.