I have a simlar set up as far as the room and fixture. If you ventilation your room properly your plants will be able to breath and expel their toxins.This will help with the temp and humidity in the room as well. You can try the Panda plastic for reflection in your room it is very durable and can be washed, it is black on one side and white on the other, that is what i use. you should buy a good fan that hooks to your light and vents out the hot air through the window. put plywood on the window and cut holes in the plywood for all venting.Good look hope this helps