Randy, you are convincing me
When I read Rons post my first thought was pulling the low spot up, that was until I read your response. Ron "could" pull it up and get going with some filler. But there is ALWAYS a way to work it up properly as you have pointed out I guess.
I was thinking, I commonly cut an "access hole" in the rear to push out things with no access, this would be an option, you think?
If you CAN'T get behind do to limited tools, using a die grinder and a cut off wheel cut an access hole in the wheel well. After your outer quarter looks good weld it back in. Unless you are doing a full on show car where the wheel wells are perfect, leaving the weld a little after welding the piece back in wouldn't be a crime.
And Ron, PLEASE where the particle mask and eye protection. There are a LOT of guys who can't breath or see today because they "just had a little more work to do". Please, do it. When you are eighty and you are told you are dieing from bad lungs, it is to late to turn back and put them on.