Hmmmmm.. I am wondering how you are measuring your humidity? Are you using a digital hygrometer? I have one girl in a tub right now (my other girl is getting switched in the next few days to a tub) and with my tub, when I first set it up, I had to put in a bunch of holes to keep humidity down. I wonder if the lights are still sucking the humidity out, even in a tub set up?? I use newspaper and a very small waterbowl in my tub, and when she knocks some water out or when she goes potty, the humidity sky rockets. I think for now I would just keep misting the aspen in your tub, to bring up humidity to 50 - 60%, it may change and be easier to maintain once you get your UTH.

As far as the cypress at home depot, you can use it, I would just check to make sure that it is not a cypress blend. The Home Depot near me carries a blend, but does not list what the "blend" is so I have never used it just to be safe (since pine and cedar are both harmful to BPs). If you do use it, I would bake it before putting it into your enclosure, to kill off any bugs, etc. that may be in there. I don't believe that any of the bugs would harm your snake, it's just more of an annoyance in having extra lil critters running around your tub.

Good Job so far in getting your BP into a much better environment!!