First, I would advise taking those dial thermometers/humidity dials off and getting a digital thermometer/humidity sensor(they sell them at Walmart in the outdoor thermometer area really cheap). The dials are known to be very "off" in the readouts and I wouldn't want your little guy to be too hot or cold and you not find out. Without a T-stat, I might consider not using that UTH just in case it does get too hot. I'm sure the lamps would be able to heat it sufficiently until you get a T-stat to control the heat mat. I would also suggest you get a enclosed hide for the one end without a hide. That way he has a secure hide in both the cold end and the hot end.

It's obvious you've spent some time checking into things for him. That's awesome because a lot of folks just jump in without researching. It looks like you're one of the really good pet owners.

They make commercially available sliding front door enclosures(several different companies), I'm not sure if I can post links to the different companies or not. Those would stack and can be bought with heat and thermostats already installed, are made from heavy plastics that are easy to clean, etc etc.

He looks like a bright colored little guy, congrats on your new pet. I hope we get to see more posts and especially more pictures of your little guy!