Closet grow setup and ventilation questions

The reason it is in my closet is because I can't let anyone see it. If I cut holes in the door that kinda defeats the point. :/

What is above the closet? If it is an attic, you could simply run a duct through the ceiling and into the attic. Install a 4" inline fan on the end in the attic and let it exhaust there. I have (2) 4'x4' flowering areas stacked in a 5'x7' walk-in closet with (2) 1000W HPS lights. I run a perpetual grow that yields 16 plants for harvest every two weeks. Ventilation is handled by 6" ducts from each light that are tee'd together and fed into the attic. A six-inch inline fan is installed in the attic and I exhaust it facing my ballasts to keep them coolerView attachment 2369762. I keep the room at 75F and the air pumped into the attic is right at 80F. Anyone walking into the spare bedroom sees, hears and smells nothing.

Can't drill into the ceiling either. :/ I'll probably do the CO2 thing.