we routinely use the Mr heaters in our stands here in northern MN. It' s spose to be -5 for opener this Saturday, so the heaters will come in handy. we use the small Mr. Heaters that screw on top of the small green coleman tanks. Each tank should last about 10-15 hrs depending on high you have them. They give off little or no fumes/smell ,and I haven' t seen a deer spook from them yet. Our stands are 15' up,so ground blind may have different results. I' d still try them. The heaters run about $18, and the cans a couple bucks. Can' t tell you the BTU' s it gives off, but I use them icefishing in my 4' x6' house and it keeps it warm inside. Steve