if the altitude your going hunting in is 5,000'-10,000' you will be just fine. There is roughly 3% less oxygen per thousand feet so that will make your propane heater less efficient but it will work. Keep in mind that propane is in a liquid state inside a propane tank and it vaporizes ( boils ) as it is being used. The colder the propane is, the slower it will vaporize. If you leave propane outside in the cold overnight it will get so cold at lower outside temperatures that it will not vaporize fast enough. When your camper heater fires up, it will shut down pretty quickly because your heater is asking for more propane than the liquid propane can vaporize. Try and keep the propane tanks warm at night. Cover them with a blanket or tarp to avoid the cold setteling on them. Try and keep backup propane cylinders in the sun during the day if it is going to be warm. Manifold two or three tanks together to vaporize two to three times as much propane as normal. Keep a well ventilated trailer, make sure the exhaust is working and buy a smoke/CO2 alarm for it. The last sentence is the most important one!