yeah i tend to do that with my growing style
simply with a closet grow, you don't need an intake and a exhaust fan, perfect example is what cletus put up earlier, from the looks he/she has a clamp on fan just to simple move air around n the closet, his door is the covering, and this is just a guess he prolly put a towel on the bottom of the door for to keep light and air from escaping, course that's only a guess though
the way i do it, is i put a panel infront of the door covering and then i put my mylar sheet on top of it, with 2 weights holding the sheet down this way it doesn't move....