Coal ovens are incredibly dry and that dry environment creates a much crispy exterior to the crust, which then stays relatively crispy during boxed travel.
On the Neapolitan side, as Nick pointed out, there's not much you can do. I, personally, don't think Neapolitan should ever be boxed.
On the NH side, there's a few things you can do.
1. Buy a coal fired oven (not very practical, but it will give you a boxable product)
2. Use the driest wood you can possibly find to try to mimic the dryness of a coal oven. Also, you can pre-dry some of your wood for the next day in the cooling oven the night before.
3. Drop the water in your formula. If you can't drive the moisture out with the oven, you can, to a point, put less moisture in to begin with.