Would need 2 fans.
One for lights, that removes the heat from the lights. By pulling air directly from outside the tent thru the air cooled reflector/ cool tube then exits the tent. This hot air needs to be exhausted to another room or outdoors. Unless using it for heat.
The 2nd fan would need to be hooked to an atmosphere controller and would turn on only when temps and/or humidity got to high inside the tent.
Almost as if you were running a sealed room for co2.
If I needed to add humidity, I would place humidifier in the room from where I am drawing my intake from. Then you would not need the fan set up I described above.