I would probably try to figure a way to use a dremel and cut out a couple small squares in the hood and place small computer fans in there, like fans that would go on a video card/cpu. One on each side of the light, one pushes in cold air/one pulls out hot air. Just a thought since I haven't done anything like that to a nano, but I don't see why it wouldn't work and wouldn't cost much to do.
The hood is hinged on the back so if you open it then it opens at an angle which isn't too good if you want to vent it that way because the light then shines into your face. If you unhinge the hood and just raise the entire thing a few inches, then your going to need something to be a spacer between the hood that is study enough to hold the hood without worry of falling. I am trying to figure out in my head how you could even do that.. lift the hood up to allow airflow, but still be sturdy enough to support the hood AND be enough to stop fish from jumping out and also not blind you. I am picturing a JBJ in a bedroom.. and if that is the case, if you raise the hood up and were to lay on your bed, your going to have the light shining in your face, not a pleasant thought.