My neigjbors got a new camper and gave me the heating and cooling mini fridge that they used on their pop up camper. I want to convert is to an incubator...it still works. Anyways it looks a lot like the exoterra incubator I have, minus the glass door. Where should I add ventilation holes, top or bottom? And where would be the best place for the pc fan, top or bottom? The heating element is a little ove halfway up the back wall.