From experience I can tell you, you will have overheating and failure problems without some ventilation coming though. May I suggest a couple USB fans drawing air through the front, out the back? They would turn on with the system and keep a supply of fresh and cool air flowing to the machines. I've replaced both the xbox and the ps3/4's because of a lack of airflow. It took about 6 months for the 3 and xbox to die about a year for the 4.