Here's what I used to get the roll on my bed sides round again.
Photo 1 photo 2 photo 3 That's a slide hammer with a big ball bearing welded on the front adapter.
Phak1 and Justhorsenround have the right idea for taking the bow out. Although I'd start with a foot rather than driving over the center. You'd be surprised how much bow you can get out with a #12 boot planted firmly in the middle.
