You don’t want the UTH to get any hotter than 90° directly where the animal can touch the floor of the cage. They will move substrate out of the way to get to it. 95° is too hot.
Screen top enclosures are hard to maintain ambient temps in. Heat rises, screens don’t contain heat, and is a very sisyphusian effort at raising ambient temps. Keep the majority of it covered with foil/plexiglass/etc and ideally the CHE should be thermostat regulated as well, but a dimmer switch can help if you’re monitoring temps a couple times daily at least.
40 gallons is pretty big for a 6 month old baby. Honestly big enough for most adult males.
Edit: didn’t see Nikkubus’s post that echoes most of what I just posted.
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