Ventilation is a two part issue........room and fixture ventilation. HID lamps get hot and will heat up a small enclosed space quickly. You need exhaust hot/stale air and bring in fresh air. Having an ocillating fan in small enclosed space will do nothing for venting the space. It might strengthen the stalks a little but that's it. You need to CHANGE the air within the space through the use of fans. You don't need 2 fans (1exhaust and 1 intake) for room ventilation.....just 1 fan and an intake grille. Remember...whatever you exhaust needs to be replaced. Not only are you exhausting the stalle air but you're bringing in the all important CO2. I can't tell you how many beginners put an exhaust fan in their space ducted outside of the space but forget that the exhausted air needs replacing. Then they wonder why it doesn't work. Look at the interior doors in your home. Most of them don't go all the way to the floor. Why? Because the heat/ac coming out of the ducts needs to get back to the furnace or the place becomes stale and overheated. Same principle with your closet.
With respect to fixture ventilation most HID fixtures have a way to attach a 4" flexible dryer duct right to the end of the fixture and connect this duct to an inline fan. Just make sure that the you get the optional "fixture flange" in order to connect this duct easily. This allows you to get the lights really close without worrying that the lamp will burn your babies.
I'm not sure I understand your "out in the open" quote. If you're gonna grow in a closet in order to manage veg (18hrs) and flowering times (12hrs) then you need a way to ensure that 12 hrs of darkness is 12 hrs of darkness....no outside light sources at all including the sun, no 12 hrs one day and 12hrs 15 minutes the next. Light leakage, screwing with the cycles or "peeking" during the dark periods can cause hermaphrodites. Once you seal the space to keep stray light out, then ventilation becomes an issue.
Lastly, odor issues. I have no idea if the air freshner idea will work or not, but considering the small size of your operation it may work fine. Just don't "freshen" your closet.....freshen the house/apt. If that isn't enough then there are 2 other choices.....carbon filters or ozone generators. Ozone generators are used by bar owners or used car dealers to remove cigarette smells.
Be careful with ozone generators though....too much ozone is not a good thing for humans. Carbon filters need replacing occasionally and are usually connected inline to the exhaust system.
Hope this helps and good luck!
