I'd put the torch away unless you have some plumbing to do.
This Army publication shows some dent removal theory:
http://www.hnsa.org/wp-content/uploa...ody-repair.pdf
...or the book "Metal Bumping", sold at Eastwood is another good source.
First in, last out. In other words, looking at that wheel well, something pushing inward caused the dent in the wheel well, and by the time it stopped, it had push in a crease. The crease was the last thing created, but needs to be the first thing taken out. The metal seems so thick because that crease has the dent locked from moving. I would pull outward on the dent while hammer and dollying the crease. Yes, that sounded like possibly more than one person doing this repair. But first, I would read those two books...