I did a similar thing but with a little twist.
I used one of these terminal strips
mounted to the inside of my canopy. Mounted two computer fans to the inside top of the canopy, drilled holes for the air to escape and ran the same DC Adapter up to the terminal strip, tied in the two fans and voila. I'll take some pictures tomorrow.
I actually considered cutting the heater off of a spare heater with remote thermostat and tying that to the fan leads but wasnt sure of how the thermostat worked exactly and since its not where I can watch it all the time decided against it. Instead I just put the adapter on a timer synched with my light cycle.
