That works as long as you always keep the doors open - or don’t have any at all.
I think it’s probably easier to just cut the cupola in and eliminate one roof penetration.
John Allin
14x18 Hemlock Timber Frame Sugar House 2009
Leader 2x6 w/Patriot Raised Flue Pan 2009
Leader Steam Hood 2014 - Clear Filter Press 2015
Leader Revolution Pan and SS Pre-Heater 2016
CDL Hobby 250 RO & Air Tech L25 Hi Vac Pump 2019
06' Gator HPX to collect wood & sap
14' Ski-Doo Tundra for winter work in the woods
Great Family 3 grown kids+spouses and 7 grand kids who like the woods
7th Gen Born in Canada - Raised in Chardon Ohio - Maple Capital of the World..<grin>.