Unless you can be absolutely certain that you know the route that your snake will take, you need to assume that she will be exposed to colder temperatures than just 52 degrees. When flying, often cargo is exposed to a range of temperatures which can be even colder as in-flight temps can vary greatly (it's been my experience that they typically don't fall below 70 degrees but we should always prepare accordingly).
Although she will be shipped overnight, you need to locate a 48-72 hour heat pack. I would also recommend locating a styrofoam container (similar to an ice chest) for shipment. This can be lined with crumpled paper, her placed into the chest in a secure container, more paper layered on top, the heat pack activated (about 2-3 hours before pickup), taped to the bottom of the lid, the styrofoam lid fitted, then the whole styrofoam container placed into a box and closed. Only use ONE heat pack. The idea is to keep the box at a comfortable temp for her, not to keep her very warm. She may arrive deceased if it is too hot in the box.
I have shipped close to 100 reptiles using this same method and have never had a poor outcome. If Pepita is small, you can use a large deli dish that has been taped closed very well and has holes for breathing. If closer to adulthood, I typically use a sizable pillowcase, place the snake inside, knot the end and place into the styrofoam container. In any case, make sure she is secure and cannot escape her containment. Here's a great video showing an unboxing, use in reverse for packing: https://www.youtube.com/watch?v=trcdmMAXetY
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