So I had new door seals put on. They really stopped the air from coming in around the door. But there is still a lot of cold air in the back row. Lots!! On my way up to Boston last week you could feel it a little, but the luggage area was literally stuffed. So I think it blocked some of the air from coming in. Midway through my visit to Boston with the plane completely unloaded I flew up to NH. If I spun around I could see my breath in the backseat. Meanwhile I'm in a t-shirt and warm in the front seat. This convinced me that having the baggage area stuffed was blocking some of this cold air. The baggage door also has a new seal and is pretty tight, but its obviously impossible for me to feel around it in flight. So where else might air be coming in? I do have an insulated bulkhead on the aft side of the baggage area with a door that velcros in place. None of this is out of place. I can't find any openings back there. I opened my pilot window at one point and my wife said it got really cold in back. So it being open was drawing even more air up from the back. The seal around this window is kind of crummy. Think its drawing up enough air from the back even though it never feels cold at all around this window?