I grow in my basement under lights, so my conditions are very different from yours. I am thinking about the dryness. Could you set a shelf unit up in front of your light source (window) that is covered in clear plastic with dishpans of water on the floor beneath the shelves, maybe a small fan to circulate air inside the plastic curtain. This doesn't help even out temps, but may help greatly increase humidity around the plants. That or keep a pot os water on the woodstove for constant steam.