As a retired air traffic controller and nearly 27 years on the job, I dealt with CO exposure more than one might think. Not me, but pilots. Pilots of small aircraft die each year from crashes related to CO exposure. It's color less, odor less and tasteless, AND it makes you euphoric, you think everything is hunky dory till you keel over.
Imagine an airplane Cessna 210, for example doing about 180 mph, LOTS of air passing over that engine, and it has a slight crack in the exhaust. Won't hear it cause there is no muffler anyway, and the exhaust does NOT run through or under cockpit. I have dealt with pilots obviously under its influence, flying all over the sky, and telling me the whole time everything is just fine. But once I talk them into opening a window, it takes about 10 minutes before they finally say they need to land. Because they start to get sick once it starts to wear off, and a bad headache. Those were the lucky ones.
I've assisted in investigations of some that were not lucky.
It is NOT worth the ease of setting a little tank up. There's a dozen ways to get safe heat from a running engine, aircooled or not. As was mentioned, go to a junk yard and pull a car heater core and fan, you will even have forced air heat and adjustable speeds.
Otherwise, make sure your life insurance is paid up, so your family doesn't suffer.