mprevo.........my shop has 3 bays and 1 window in each. We put a furnace filter in 1 window and hung plastic sheeting around the car. Then we put a turbine type fan in the middle of the floor at the door and blocked off both sides of the door with cardboard, taping everything tight.
This type of fan moves volumes of air. Using a common blade fan will disturb the air and allow the overspray to hang in the air and not be pulled out.