jims,
I don't know if you can find one, but I use a Coleman Propane Radiant Heater with a 3500-5000 BTU adjustable input. It uses the 1# bottles. It has a 6"x11" adjustable reflector on the front and is very lt wt, about 3# including bottle. It has Electronic Ignition and no matches are required.
It also is very stable with a 7'x12" footprint and will not tip over. On high it is very quiet and ten yards from blind you can't hear it working. My son and I use it in our Double Bull ground blind when the weather turns real cold and the blind measures 6'x6'x 6' high. Set on low it will keep the temp inside the blind @ appx 60 degrees and on high it will get up to about 70 degrees. You can comfortly sit without a coat, gloves,hat, etc on, or for that matter boots either, if you want to warm your toes.
I have never experienced any problems with carbon dioxide with only a small amount of ventilation. I have used this heater for over 3 years and am so impressed with it, if I could locate another one I would buy it for a spare.
A hunting buddy of mine uses a Mr. Buddy and he likes it also. When the going gets tough and you want to stay out all day you can't beat a good blind and a propane heater with a heat reflector.
For the hard core guys that want to hunt out of a treestand or still hunt on the ground when it gets real cold can still use this as an option for a place to go to warm up and to rest, eat, etc and still be out hunting. I would definitely get one.
IMO this is a must have hunting accy for anyone who hunts out of a blind when it gets bitter cold.........Good Luck!
Pocampo