Hey! DP out of the woodwork, how 'bout that!
Agree with the others, Trevor. You've done a great mod there and it should serve you well into the winter months. Just remember to let the air settle for 15-30 minutes after switching the cooling off (and before you start imaging).
At the moment, I use a power-point timer to turn the unit on and off. Eventually you might want to get tricky like Anthony, and have the temperature sensors feed back into a computer to control the switching on and off of the unit, so you can leave it running all night and know that when you get up at 4am the mirror is at ambient.
Once I left mine on too long and when I got up, the mirror was all dewed up from cooling to 2 deg below ambient.
I had to get the hairdryer out to get rid of the dew/fogging up until the mirror warmed up a bit