Yeah i have to vent the hot air back into the room with the tent because i live on a built up estate and have lots of neighbours directly facing my house so i cant be running a pipe visible out of the window its too obvious...so to combat this i just leave all windows open during lights on and close em when lights are off. I know it would be better to vent directly to outside through a pipe in the wall or into my loft but i cant as i live in a rented house.
i would always recommend going from room to room or into the loft or whatever rather than outside unless you live somewhere where being
inconspicuous is not important
fan makes a fair bit of noise on the outlet and is visible, to neighbours and folk who walk by
when the lights switch off and there is a rapid humidity drop a strong cut lawn/grass like smell wafts out of the filter, even when you run ozone with it too
so i like to keep it all inside,
i know you said its rented, you could make a small hole in a joining wall with a diamond bit core cutter, you can rent those
they cut through brick very neatly without cracking the bricks and you get a long shaft of brick/concrete you can put back after.
no one would ever know lol
if you cant extract the air out, you could bring new air in directly, that would be the 2nd best thing rather than the re-circulated air in your room getting sucked back into your tent,
you could use an inlet fan to suck colder air in from near a window and blow it straight over the plants, this air will have more co2 and be cooler than the air in your room
peace