There was a discussion about bunk replacement years ago here on C.C and a catfishing website. Never use treated wood with an aluminum boat, ok with a glass boat. Don't know if it was the older green treatment or the new yellow treatment. The yellow treated wood doesn't last as long as to green treated for sure.
Wilson Lumber Company in north Memphis, TN was the only dealer with cypress in the area. I could have driven farther south and got fresh rough cut at a better price. I wanted longer bunks, measured and placed an order, picked up within the week. Measured old bunks for bolt hole placement, Mine had 3/8" galvanized bolts a bit short for the new wood. New longer bolts, Holes drilled in new before old bunks removed. Carpet cut to width needed. Launched my boat and brought trailer back to campsite. Replaced the bunks, used 1" roof nails to apply carpet. 5/8" staples wouldn't hold carpet in place. Removed the old carpet from the bunks for trash and bunks for firewood. The old staples were 1" long.