No outside fans installed on our fridge and our dual fans on the inside are mounted about center on the fins. The dual inside fan just needs to move lots of air and discovered that they are considerable more efficient than the small battery powered stand alone units that we initially used. Our Dometic has performed well from day one, adding the dual interior fan reduces recovery time and keeps temps consistent throughout the unit.
No need to have interior fan go off every time you open the door unless there is cause to keep it open for more than a couple of minutes. Yes, cold air does escape but that has little effect on the temp of all the items within your fridge. When door is closed the dual fan allows quick recovery with the help of all the cold items within. Ours runs 24/7 whether we have hookups or when camping off the grid, current draw is minimal and has little impact on our 12 volt reserves.
