Dumb Noob Question. But Need Help None the Less

Okay, so I am almost totally set to get my grow up and going and I just thought of this question.

My tent is 3x3x5, I have a 400w MH/HPS light, 6" 400cfm inline fan and a 6" carbon filter. My plan is to use passive intake for my fresh air, using an open panel in the tent with a HEPA filter over the panel to keep dust and bugs out.

Here comes the dumb question. When I get to 12/12 lighting, how will I keep the light out of the tent?

I'm afraid that if I close the panel at night, the temps will get too hot in the tent. How do you all solve this problem?

exhaust fan

are there any unused intake ports in the lower half of the tent?
your gonna have to run ducting into a port (preferably several) in your tent and use it as your passive intake, with a few bends in the ducting.
we just had to noodle out the same problem, +rep

The lower half of the tent has 2 x 4" ports and 1 x 6" port, plus three vent windows. I was thinking of using the vent windows for my passive intake. I had not thought of running ducting through the bottom of the tent to use as passive intake. You wouldn't haven't happen to have a pic of your set-up, would you?