This is a great tutorial for packaging eggs. I do it this way with a few variations.
https://www.backyardchickens.com/a/wrapping-packing-eggs
To simulate what your eggs have to endure and survive, take a shipping box and hold it over your head. Now drop it. Then kick it. Tumble it end over end. Maybe even down a flight of stairs for good measure. If your eggs come out unscathed and intact, they have a decent shot at making it though the postal system.
