Well I sat in a blind today with one of 2 like new Mr. Heater units I bought this past summer at a tag sale for a total of 8.00... these things cost 100 bucks new.
Anyway I had been in the propane business for 10 years so as far as any safety issue or concern of blowing up there is none, (I have been involved though with houses that have blown up, totally gone with just one 100 lb cylinder, 24 gallons of propane..not pretty). I hooked each one up to larger propane tanks, one with a 20 lb grill tank that I hope will last all season and another with a 10 lb propane tank which can easily be refilled but lasts 10x longer than the 1-lb cylinders you buy...and much cheaper.
As far as I can see it didn't bother the 2 does that walked by my blind at 15 feet either.
There is no noise that I heard nor was there any smell, and you don't need to bundle up either, I have a piece of rug to insulate my feet on the ground as well as those shoe insert heaters now sold and I was toasty.
I just wish I can somehow mount one of these in my stand. Ms B, you have a good idea using the sleeping bag, that would be excellent for a treestand without spending 200 dollars or more for one of those heater suits.
With all the deer you may have taken there holds in your memory a special place i'm sure for each one you killed.