I agree with you.
I'd peen it at several places in the middle but I think I would not use a punch, I think I'd use two ball peen hammers. Use one of the hammers as the punch and tap it with the other hammer.
This will spread the distortion of the metal over a larger area and reduce the likelihood that the hand will break from metal fatigue where it has been peened.
I think you might find that if you peen it only on one side, that it will wind up bent slightly in that direction.
Best of luck with this project.
My reading of history convinces me that most bad government results from too much government. Thomas Jefferson