I am setting up an arch that will need 2 expresses in the same location. I have decided to use one enclosure for this. I will be using all leds so I dont think heat will be an issue. I used #8 screw 1/2 inch. The screw penetrated a tiny bit, I plan on just coating the screw with a little silicone sealer. I cant post pictures for some reason so I will get someone else to post the picture.
Brad