I've shipped 5000's to Connecticut and 5500HC to Toronto from California. With original Meridian packing, the 5000's qualified for UPS or Fedex weight limits and the shipping was reliable. I used UPS and these went as separate boxes, not palletized.
The 5500HC is too heavy for them and I didn't have the original packing materials. Here's what I did.
1. First wrap in saran wrap to avoid scratches, etc. Do this on all speakers you ship.
2. Use heavy duty bubble wrap, several times around.
3. Then obtain a large packing box from a shipping/box company;
4. Re-inforce the bottom with foam or heavy cardboard.
5. Then place it over your bundle of 5500+bubble wrap; the re-inforced end is on top!.
6. Turn the entire package on end so the re-inforced end is now on the bottom.
7. Use another slightly larger box, re-inforce it's bottom and place it over the upright speaker and box.
It should be a tight fit. Have your shipper band the box. He probably will ship it on a pallet using a freight company. You can compare prices with UPS freight option.
It can be successfully done, just takes a lot of effort on your (the shipper's) part. Hope it's appreciated by your buyer. Good luck.