A friend sent me some eastern diamond back skins that were well over 6' long, the patterns were much to big to fit and look good on a bow, I thanked him but sent them back.
Another thing; check with your state laws, it is illegal to use snake skins in a state where killing them is banned. The fines are huge and the game wardens can confiscate your bow.
I gave a impromptu selfbow shooting demonstration at Davy Crockett park in Lawrenceburg Tn once, my bow was backed with copperhead skins that I bought from a guy in Texas. Turns out killing any snake is illegal in Tennessee, two game wardens were in the audience. A guy near them said they had an issue with the snake skins but decided to let it drop and didn't approach me. I got lucky that day, I quit taking any snake backed bows into Tennessee, I hunted on various leases there for at least 20 years and did get checked by a game warden once.