Just run a fan on it. I have run a 10xl and 9xl on 16 cells and did fine. If I were you, run the 9xl. you can gear it up and it'll stay cool. If you are sticking with just 12 cells, go with the 8xl. Then you could run 12 or 14 without problems...i always run a fan on the controller as extra insurance. They're not all that heavy, fairly cheap, and hell, why not?
"if you've got something to say, say it peacefully"