save a few bucks and go to Home Depot or Lowes, go to flooring dept. where they have the rolls of bulk carpet up on the wall. Pick one that has a rubber backing. It aint gonna say its marine carpet. Get one of the indoor / outdoor ones. Buy a bulk piece and cut into strips for the bunks.
I would take the bunks off the trailer and recarpet them. I wouldnt waste the money on ss staples. They are not necessary. ( and I am king of overkill.) The first time I recarpeted bunks I used regular galvanized staples out of a handheld manual staple gun. The staples lasted longer than the carpet. But, if you have access to a pneunamtic staple gun, use some 7/8" or 1" staples.
dont waste your scratch on internet ordered per cut marine carpet. I wont last any longer than the stuff you can get at the big box stores.