You might try a wash with vinegar on a scrap piece of copper. I too built a large model of the Cutty Sark, but I just painted her hull with copper colored paint. Your use of copper sheeting is an excellent concept!
I was thinking of getting a ponce wheel from Micro-Mark so I could roll a line of simulated nails. I don’t know if Joans fabrics and Crafts still sells those rolls of copper what with the price of copper, I bought that roll about ten years ago.
Now I have seen some very very nice wooden models of Old Ironsides, but the problem is they are mostly from Vietnam or some place and the scale is either off or the authenticity, a real scale period piece in wood, brass and copper is spendy.
That is for an as built, I have catalogs for kits from solid hull to plank on hull. I have four large wooden sailing ships, each are from overseas and are from 3-4 feet long, the Cutty Sark, Flying Cloud, a four master cargo sailing ship, and the schooner Bluenose which is the largest and has the best hull finish.