Hey smalltown speed!
Been there done that.
It's not impossible.
You can see pics of mine here
http://www.hotrodders.com/forum/journal.php?action=view&journalid=20255 Just ignore all the rotary stuff.
I had to do quite a bit of fabricating on a truck that initially looked solid at the lower back. My guess is because the Burb has the windows it lets more moisture run down into the lower fenders where it gets trapped by accumulated dirt.
I did use a rocker panel to fix the section between the back of the door and the rear fender. It was very helpful leaving (as red58 explained) only some creative work to do around the wheel well.
