I also agree that you won't get alot of heat disapation by trying to pull air from the basement. We're not sure of all the conditions you have (tank size, type of lights, etc...), but a small fan or 2 blowing into the canopy, across the water does wonders. In my humble opinion, if you are willing to cut thru the floor, then I would be looking at putting a fuge or sump and other equip into the basement.
It would be very easy to control temp if you were pulling out of "a reservoir" which is at a cooler temp (guessing 65 degrees). You also wouldn't need anything "fancy" in the basement. Chances are, with a large fuge, DSB, alot of cheato or vegetation, etc... you may even need a heater on the whole system year round. I always thought one of the best parts of a "sweet setup" was all the invertabrates and other items that you could put into a fuge.