Your still gonna want to watch that heat with the HPS. Just make sure you have enough vent for the heat. The best solution you could do would be to find a window, crack it, board it up, put a hole in the board big enough for a rat cage fan, then tie a tube to the fan that leads to a vent'd hood. The exhaust from the hood will go into your grow room, but the bulb will stay cool and the room should stay a nice temp. The only thing i dont know is what an outside of near 0F would do to an HPS bulb, but it should help with the heat alot. Then you can have an exhaust fan in your grow room that would go outside or where you want.

Hope that helps.