Thank you for taking the time to respond. I have two thermometers (that measure humidity too), one on either side of the cage. I have seen on this site that a lot of people mention a thermostat, so if anyone has recommendations for a good one, I'd love to hear it. Same goes for a temp gun, because I've never heard of those. To create more heat, would you recommend a long light that goes across the top of the cage, or just a second light on the cool side attached to a thermostat? I'm very interesting in the insulating foam. Is that something that would go on the inside walls? As far as humidity, he has a large water dish and a small one, and I mist the cage almost every morning. Is there a more efficient way to raise humidity? As far as feeding him in the cage, I put the mouse in the plastic bin instead of on the floor of the cage because I was afraid he would inadvertently eat substrate along with the mouse. Do I not need to worry about that? I also like your idea about putting the plastic tub in the cage as an extra hide. Should I color the sides of it (it's clear)?
Here is a link to the imgur I attempted to make:
https://imgur.com/a/1jyJGVx