i don't see a need to heavier than pvc drain pipe. it can take some serious throwing around. what it and schedule 40 can't survive are fork lifts, crashing 100# tail gates and conveyor belt gearing snafus. going to bomb proof packaging is paying for "shipping mafia protection" and i won't give them my money.
that means having adequate insurance and using a shipper that will *eventually* pay you back.
in my experience, the usps is best as long as you have a valid manufacturer's bill of sale clearly stating the item and its purchase value- without that, DO NOT even bother with insurance. i'm serious. this is true for both ups and fedex as well, but ime usps pays promptly (one month) whereas even if you follow all the rules those other shippers might not pay - happened to me with ups.
ALSO, your packaging counts big time - ship a bow in a cardboard box that gets destroyed and the shipper WILL tell you that YOU did not use the proper protection and therefore YOU are negligent and not them.
so, for shipping one piece bows, i recommend using usps priority/insured, use a decent pvc or reasonable carpet tube, cap the tube ends *securely* (i typically screw in 1/2" ply discs), be able to produce a proper bill for the bow yer shipping, and hope for the best. use or do anything less than this and you will need divine intervention! :D