You have the foremost temperature expert just up the road............Bird!!
Paul Haese has added peltiers to his c14 and it works a treat. As mike says, canberra sux (like tasmania) for constantly falling temps.
Basically, your mirrors never catch up.
THere are a few designs floating around where you can get the lymax blowing cold air inside........some guys will put the OTA in a fridge.
I have a feeling you will want to go peltier cooling
