This type of heater is not the quick heater like your furnace. You might also need to run the oven a bit or the stove burner to get the camper warm after a hunting trip, as the Wave 3 will take about 15 minutes to warm up. Still it will be warmer than being outside.
Same thing as the Mr Buddy heater - leave a window open about 3/8" and the roof vent 3/8" - 1/2". I have Maxx Air vent covers over all three of my roof vents, and I leave all three open just a small amount, to let some hot air out, and cool air is made up through the kitchen window, I am not to worried about rain coming in, it is all formica there.
I have the Olympic 6000 Btu model, on feet, with my quick disconnect coming out below my oven, to the left side, next to a wall, so I will not kick it. It has worked great since 1997. ..
Mine is on feet, and stored in the closet when not in use.
Good luck hunting and have fun camping!
Fred.