Overdriving on an 8" deep tank is not the greatest of ideas IMO. You will more than likely fry everything that goes in there unless the lights are like 20 inches away. JMO though
I would use the Ice Cap's over the Teks.
So I could either raise to 20" or probably better yet swap out the 660 for a couple workhorse ballasts so I'm not wasting so much electricity?