Thoughts on my quarantine setup?

[Bogertophis]

I'd lower the temps. some (hi & low) for a BCI, unless that's what the breeder is telling you? I had a BCI for many years & she preferred a bit lower temps., &
I understand that's typical for them...they're not the same as BPs. Her behavior should tell you what she wants also.

Your CHE over the "cool side" might be too warm? -unless you're just planning ahead for fall & winter? But for having CHE & UTH on thermostats.

You might want to adjust the wattage of the CHE you're using after you try it for a while: I don't use CHE, but I've heard they tend to burn out faster if overly-
regulated (by thermostat, on/off constantly)...if true, it's something to be aware of.

I'd wait to add moss to a hide until you're sure there's no mites...they like hiding places like moss & it doesn't take many eggs to have a big happy colony of them.
Otherwise, looks pretty good...minor tweaks are all I see. Great job being prepared ahead of time! So many don't do that.