When I shipped a large male lesser, I put a layer of good quality large cell bubble wrap into the bottom of the box, to provide added cushioning against rough handling (specifically, the box being dropped). I only put it in the bottom, as I wanted to maintain adequate ventilation. I used lots of crumpled newspaper. My feeling is that larger snakes have a harder time of it. Pack extra cushioning in, and don't leave any empty space. Always pack the animal as though the box will be thrown down a flight of stairs, because once it's out of your hands, you never know!