Years ago, a guy I know came upon one like that, in the woods near his house. He put the stock of his rifle on the head of the copperhead, and picked it up. The snakes head was too far from where he grabbed it, and was able to reach around and bite him on his thumb at the knuckle.
He said it was like fire right away, and he sucked the wound. His teeth immediately started to burn and ache. Him and his buddy jumped on their dirt bike and hauled ass to his house near by, and took off in his car to the hospital 10 miles away. He said it took less than 20 minutes to get there.
He said when they got to the hospital, his hand and forearm had swollen up like a surgical glove blowed up with air. A cut on his hand started to split open. The doctor said they would try to save his arm. The doctor also said they don't give anti -venom most times, as it can cause more problems than help.
They took him into surgery, and cut him open from the thumb, up his forearm, to the crook of his elbow. They surgeon must have had a sense of humor, as he made a curvy snake like incision up his arm. This was to let the swelling drain for a couple of days. They then closed the wound and he healed up fine except the bite site, which turned black and took a long time to heal. He does have a cool scar to show off.
Oh, and he lost a bunch of his teeth soon after.