First, thank you all for your responses and thoughtfulness towards our wellbeing. I always err on the side of caution when it comes to health and safety, and have been venting outdoors since I started painting last month.
(In the middle of all this, I learned of the unfortunate passing of Toshi last October. While I did not know Allen well, he was clearly a bedrock of this community and an all-around amazing guy. My condolences to all of you that are feeling the pain of this tragic and untimely loss.)
Here in Eastern PA, summer means humidity and mosquitoes galore, while winter brings with it frigid temperatures and unpredictable precipitation. If I am to continue venting to the outside, clearly I need to come up with a better solution.
Unfortunately, I do not have the means to build anything from sheetrock or plywood. Any solution would need to be temporary and easy to put up and tear down.
The gap in the doorway is only about an inch or so with the duct in place. What if I cut a strip of heavy duty cardboard the height of the doorway and a few inches wide, cut a hold for the duct, and taped it in place? If I use strong enough tape and decent cardboard, it should hold the weight of the duct, no?