Myself would add a small domed fixture (Fluker's) with dimmer and a 60W Ceramic Heat Emitter. Another option is an incandescent red bulb (or two) on the ExoTerra top; but those ExoTerra tops can only handle low wattage bulbs so need to test it. Also, could try a large heat mat affixed to side; but be aware they are highly inefficient in that position. Good luck !