Thank you SamG for the pictures and ideas, they are a lot along the area of my larger need as well.
The "accident damage" I need to work on was a sideswipe damage that occurred before I purchased my car and resulted in a replacement door, fender and a repair to the same area of the quarter panel you have pictured. On my example, the sideswipe damage grabbed the "peak" of the lower body line and drove it back about an inch or so, creating a huge cave-in at that point, without caving in the "B" pillar and without making it's way rearwards into the wheel housing area at all. I do notice a little damage I'll need to work on in the lower hinge area of the "A" pillar, but it was insignificant enough that the hinge adjustment had the door fit and close good for over 20 years.
This quarter panel damaged area however, was pushed back as good as we could get it in 1978 (my 17-year old brother and my 16-year old self) but today needs to be done better so last night I went "INVASIVE".
I cut out some areas of the front wheel house and opened up the end of the rocker panels (removed more mouse nesting from inside the rocker panel) but the access hole gave me a chance to straighten things like I was never able to before. I also cut a slit where the section of quarter panel wraps onto the "B" pillar to relieve some of the wrinkles still in the metal. Using a 1/2" thick by 3" flat bar, I ironed out most of the wrinkling.
I will likely update this a bit more later, but at this time, I might be using most of my original metal pieces I cut out over again! I tentatively have located a replacement "original" section for the accident damage, should I wish to go ahead and replace that like I was seriously thinking I might yesterday...but things are looking better after a few hours of chopping, sawing, drilling, pounding and grinding yesterday! There are only a few areas of "rusted away" metal, and the "iceberg" Bob spoke about wasn't any where near as big as what sunk the Titanic! (thank God!) The rust was truly isolated to within an inch or so of the visible areas seen on the outside.