First I would move the water to the hot side to increase humidity. I have my screen top completely covered with 3 layers of aluminum foil with 1" gaps on each side for circulation and a hole cut in the center for my red light to shine thru to keep up ambient temperatures. My tank is only a 20 long and I have no problems maintaining 50% humidity with no misting.
When she starts to shed I use a humidifier in the room and can maintain up to 70% humidity consistently.