Cooling a closet grow

I'm growing in a small-ish closet, just two plants under a 150watt HPS with three supplemental 42watt CFLs. I have an exhaust fan blowing about 300CFM with two oscillating fans circulating air.

My problem is, this is Florida, and the light-on temps in the closet usually hover at around 84-85 degrees, which is right at the point where the plants will close their stomata.

My intake is limited to a 4" duct (same size as exhaust). What tips do you guys have for bringing those temps down a bit? Intake fan? I've thought about changing the photoperiod so that the lights are on at night and off during the day, but like I said, this is Florida and I don't know how much of an impact that might have.

Any hep would be appreciated. Thanks.

My average temp is @ 85 degrees also,I've read that temps in the mid to high 80's is ok.Go out to home depot and get a return duct.5in x 8in.Cut a hole in bottom of door.Put one of your oscillating up higher than your lights and point it to the door.I beleive they call it a "passive" system.What ever that means.I know that the air blowing on the door will travel down the door and suck in cooler air from outside your closet.Thats what i did.It helps out a little,but again im in jersey not florida.Big temp difference.