Pullin out a dented rocker on a mazda,

ok, on my mazda project the driver side rocker panel is dent in, but its just like a smooth round dent, that can be pulled out, whats the best way to get in behind it to pull it out, i can cut out underneath the truck behind it and push it out, i can drill some holes and pull it, what do u think is the best way, weld a new piece in, ???