believe me the smell will get out regardless of what you do, infact it will build up in there and really start to stink the place up, is there a door to this setup you could leave open but a few inches?

this is probly the biggest issue people have and there really is no way around venting the area, is there a reason why you cannot cut a hole in the closet somewhere....even the roof of the closet with a fan pulling out would help you greatly.