The humidity issue can easily be solved by misting regularly, if this is not possible, there are automatic misters that can be purchased, which I am personally not a fan of. I am in Southern California, it gets plenty dry here in summer months so I can relate to your concern.
I also have never liked using heat lamps. You can add heat tape as a supplement to the UTH but definitely use a Ranco or JC with it.
I have never used repti-carpet but curious as to why you would think a towel would be an inhibitor for bacteria? Regularly changed out, it should pose no bigger threat of a breeding ground for bacteria than any other substrate that is not changed regularly and maintained. I have been using MF towels successfully for 10 years. I get the added bonus of never having to worry about introducing mites or parasites into the husbandry from a supplier.
Just a side note, if you run your house heater regularly, there is no more effective way of De-humidifying the ambient air in your house. I would even go as far as to set up a humidifier in the room to counter this, but I think that is excessive. Perhaps the glass aquarium makes it harder to hold humidity than plastic tubs, which I use, but I have never tested this and so can't back it up. Merely a suggestion.