I can see your pictures with link you posted, could not see them in previous message. They usually use a pick or wedge shaped hammer to straighten dinks in trim work. Use a piece of hardwood to back it up
or possibly the flat face of a small hammer.
It takes alot of time to straighten it right.
The rear bumper might be able to be straightened somewhat if you had a way to pull it back and down but doubt you could get crease completely out of it. Is front bumper painted or chrome? If painted you could probably straighten it some with a heavy hammer and fill and repaint. If chrome,
it would probably chip if try to straighten.
I don't know if this is any help or not. Maybe some of the others may have better ideas or first hand knowledge.
