I use Repticarpet for some of my girls, it is antibacterial and pretty easy to maintain. I also strew fake silk leaves on the floor and have some glazed ceramic flower pot saucers for them to rest on if they want to get off the carpeting. Humidity is fine so I'd keep it simple as possible. When you use natural substrates they can become bacterial breeding grounds if you already have an issue. Too much humidity for these guys is definitely not good, as you're looking at respiratory and bacterial problems. WTFs do handle a wide range of temps/humidity/environments, but since you already have problems with your gal it's much better to err on the side of caution. :/