mugz i use exactly what you are talking about. Been using it for about three years now and it works fine for me. I go through about 3-4 tanks over the winter.
THose work great I use one in the ice fishing shack, and it takes the chill out. I would invest in a couple of rolls of insulation, some staples,and some plastic that would be your best bet.
Order a 100 lb tank from the propane company. Worth the hassle, that way you won't run out just as you start to spray!!
And leave it outside also, never had a problem with it out there even at 30 below.