J.. I have been struggling with this myself... I bought this awesome LuminAire hood. Problem is that the thing is massive. It also weighs quite a bit. It was taking up half of my 3x3 tent and adding ventilation to it was a complete pain. There just isn't space in my tent for that monster.
Finally my hydro guy hooked me up with a 4" air cooled hood. It's a Sun System hood and it is air cooled. I think he mentioned that he had to buy the flanges and glass for it. It would be easy to do yourself. THE BEAUTY of it is that the flanges are on the sides so I have plenty of room to run 4" venting to the hood. Most air cooled hoods have venting on the long ends. This thing fits great in my tent. You may have to email them and ask them about air cooling this hood. PM me if you need any help or pics or whatever.
There is also this one.. I emailed HTG and they recommended this since I could buy the 4" flanges.
http://www.htgsupply.com/Product-SuperNova-Reflector