Hey there,
I have a reptile basics VE-6. My temps seem to pretty locked in, 90F hot spot with belly heat. 80 degrees in the back of the tub and around 72-73 in the front of the tub. You might be asking why the big fluctuate.
Part of the reason, my rack is in my basement and the ambient temp stay about 66F all year long. Unfortunately setting up heaters in my unfinished basement wont work because I would need 2-3 of them to get the temps up. My basement is fairly big with 10ft ceilings.
Also, it should be noted I have had my collection in the basement for almost a year now, all snakes eat really well, shed great, and are healthy.
The big issue I am struggling with is the humidity in the front of the tub. I am currently using Repti Chip and when I change it out, I spray it mix it up and then mist when it starts to dry out. The humidity levels usually stay around 75-80%. Sometimes a little higher when it is first changed out but is only higher then 85% for a day or so as it starts to dry out.
No matter how many holes I put in the front of the tub or in the back, I consistently have condensation in the front of the tub and have to wipe it out every day, see pic. The issue with this water in the front and if the repti bark is in the front (which I try to keep away) the water will soak, the bark will get overly wet and mold will start.