Can I beat this with a hammer (rear tire well)?

I am interested in relieving a little above the tire in the outer upper wheel well on the rear.

Shown in the pics circled in black, highlighted in green, are what I would like to massage with a hammer.

My main an only concern is distorting my quarter panel where it interfaces with the wheel well since the wheel well provides support to the quarter there.

Does anyone have experience with massaging this area?

Thank you.