True, yeah South Dakota, Black Hills. I've been out there for some major cracking, seems to stay pretty quiet when its colder and there's no direct sun on the ice. I don't have a CO detector but we're not running the heater at night and will sleep with a vent open... 3 of us on cots plus doggo. We've camped next to an iced lake before because we were a little too jumpy for the 4 inches of ice that was out there.. just want to triple check that we're okay on 12. Thanks!