i have the same problem in a way,i would say get an inline carbon filter,and a piece of shit door.
depending on the vent size,cut a hole in the top of the door(for the vent to go into your house) then cut about an inch off the bottom of the door.
draw hot air out the top and the cool air will replace itself though the bottom,keep it on all day long and it will keep constant airflow.day and night hot and cold,actually help heating your house when the light is on.
try also light on at night if light is sealed enough,cuz the night is colder of course.
this should help,if you can run it this way.
good luck and keep on growin