Live plants are your missing component. You may need to add solid side panels to the back and the two sides as well. Most of us fog into a cage at night rather than having one run in the room. It is easier this way. I would not get a larger unit. You do not want to deal with mold or damage to the room because your pumping so much humidity into it.
Plants really are the big hitter when it comes to increasing natural humidity. They are also better for the cham providing hiding places and temp/humidity gradients in a cage.