You mention "as close to factory as possible"... here is a photo of the stock "factory" set-up with the notched fender on a longbed stepside.
http://inlinethumb33.webshots.com/48544/2699912630103882008S600x600Q85.jpg

In regards to needing the notched fender I'd suggest setting a tire on the step and seeing if there is enough room, kinda depends on the diameter of tire you are running.

You could make your own bracket, I fabricated one out of structural steel for my shortbed shop truck.
http://inlinethumb40.webshots.com/28711/2886424430103882008S600x600Q85.jpg
http://inlinethumb12.webshots.com/49611/2743143930103882008S600x600Q85.jpg
http://inlinethumb08.webshots.com/50311/2375730440103882008S600x600Q85.jpg



In the Stovebolt Gallery ~~ "The Orange Crate" 1965 C10 SWB Step Side Build Thread

Inspired to be different. Different in a way of my own, not in a way that others strive.