Hi, I'm new to shipping reptiles. I need some advice on what size box to use for a 970g ball python. I've searched and see recommendations for both the 12x9x6 and 15x11x7 but I'm not sure which one would be best because most people only talk about shipping hatchlings. I feel like 15x11x7 might be too big but I'm also unsure of whether or not the 12x9x6 is too small lol. Also, do I need a heat pack if temps are in the high 60s-mid 70s from my location, but in the 40s-50s at the destination?

Thanks!!