Heat is the tough issue for many. We used insulated duct and insulated the light hoods. It was easy to do before the plants were put in the room. Like you I have the AC lights, but I felt way to much heat would transfer from the ducting and light hoods to the room. I also have the ballists in a different room for the same reason. But you could insulate the hoods and your duct work. See the pics of my grow room:

http://boards.cannabis.com/indoor-gr...ml#post2100306