I've decided to pop in because I too start my new hatchlings in a 10 gallon aquarium. It took some refining and it requires some diligence to maintain heat and humidity but it is doable.

I did most of my heat/humidity calibration before brining my snake home to avoid him having to live with my trial and error shenanigans.

I have 3 sides covered with foam board like you do. I'm using an UTH with the thermostat, and currently a 60 watt IR heat bulb also on a t-stat. My top is entirely covered with an acrylic sheet with a quarter inch clearance around the lamp dome. I live in a rather arid region so humidity was probably my biggest issue. Switching to a coco substrate helped a lot. When it is not winter and the heat is not blasting I can get away with misting every 3-5 days. Now that the heat is on I mist every other day and everyday when in shed.

As for your temps, where are you taking them. If you are using wall gadges you'll get ambient air temps and if you are trying to push those up your surface temps could get too hot especially under the lamp. I use my thermometers to give me an idea of where I'm at and use my my handheld IR thermometer to verify. You will lose heat when you open the cage for feeding and handling and misting. At long as the snake has his hot hide with UTH he has some place to retreat to.

I'm also going to recommend feeding him in his cage. If you are getting nipped it is likely defensive and not a feeding response. Baby ball pythons can be very nippy. This should improve with time and proper handling, but get him eating before you do more handling.

To thaw I place my rodents in a bag and float in warm water. It usually takes 30-40 min for something of rat pup size and I'll flip it over half way. Once thawed I'll hold the rats up to the heat lamp to warm the heads then feed. If my snake is being a bit slow to peek his head out I can hold the rat under the lamp again to maintain an attractive heat signature. If that doesn't work I leave the feeder in the cage, turn down the room lights and walk away. If he isn't working at it after 30-45 min I count it as a refusal.

As for your feeder size, I got my pied female at 114 grams and the breeder had been feeding her rat pups, and that is what I fed her, she is a voracious feeder though. They are capable of taking them down fine at that size, but sometimes a nervous feeder may do better on something smaller until they get used to the goings on of their new life.

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