If you could post a photo of the enclosure, it would help. Keep in mind, it is late and I am tired, so hopefully I read this right.
first thing is take the heat mat out of the tank and put it under the tank. take the thermostat from the red light and hook it up to the heat mat. Get a rheostat or dimmer switch for the red light. Definitely put some type of guard around the light so your snake can't get to it. If you have the tank set-up in a room with a window where normal daylight comes in, then you don't need the white light. If you are worried about it, just take it out. The normal daylight will be enough to let them know it's bed time. If you need extra heat for the ambient temps then just keep using the red bulb but please put some type of guard around it. Yes, the heat lamp is probably contributing to the low humidity, but until we can actually see what you've got it will be difficult to make very many suggestions.
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