Shipping doughnut batter?

I am shipping some doughnut batter to a friend. it already rose and is in the traditional doughnut shape. I have frozen it. What would be a good way to ensure that they are safe for him to cook up when they arrive after days in transport. it must be a rather cost effective way, i.e. cheap to ship so I can't just send off an ice box; that's far too expensive. Also can i just freeze them and ship them out then they can thaw out in the journey? How should he store the uncooked batter once he receives it? I know the batter can last months being frozen but what about this transit thing?