Yeah, Toyota. That's how I pack virtually all of my plants for shipping. Most make it just fine. Sure, there are always some that don't make it, but that goes with the territory of weather changes and using the postal service.
I've also found that the cheap pillow stuffing (like filter floss) you can buy at Walmart ($2.79 for a huge bag) works pretty well as an insulator if you're paranoid about a plant making it. Wrap plant in wet/damp paper towel, seal in ziploc bag and line box with pillow foam. It's very lightweight as well. Works good if you're trying to keep it under 1 lb.
Location: San Francisco (mainland transplant from Hawaii)
I splash a bit of water into the bag, I am talking about maybe a teaspoon of water. But plants will actually ship better dry (no papertowel, with just the water on the plants) than with a paper towel. This is how I see it filter floss>dry>damp towel>wet towel. If you put any bit of water into to the bag you are still creating an envioronment of 100 percent humidity. How can plants dry out?