As someone who have imported 90%+ of his N scale collection all I can say is go overboard rather. I've had locomotives land in pieces. Sometimes broken. Micro Trains wagon in their original parts disassembled.
I've always had a suspicion that the Post Office have a contract with karate to have them practice their chopping moves on our parcels...seems like that when they arrive.
I once bought a set of 8 MT flat cars in a box in foam. Of the 16 MT (small KaDee) couplers 5 were broken. Some snapped, other had pieces broken off. Turns out foam is not a good way to ship...parts sticks into it and lodges which them prevent any movement.
I hope it all goes well for your shipment. Do report back on how it went...
