If you think fan noise could be an issue, look at the second fan on this page. I have four of them in my computer case, and if you turn the fanspeed relatively low, they are essentially noiseless. I don't know if you'd intended to use computer case fans, but if you did, these things would be a good option. (Maybe even put a small hole in the back of the box and place the fanspeed adjuster there, so someone could adjust the speed of the fan on the back of the box if they knew it was going to get very hot during extended use).