What goes here between the rear fender and the rear bumper?

[Speartip]

I believe that is the plan for mud flap . I was just thinking if additional piece was pulled out to be even with outer fender it may look a little cleaner . But as he mentioned than there would be gap between addition & tub .
We will know more when his mock up is complete . I’m inteseted in this as I may do the same .

 

[WestCoastDan]

It will appear similar to this image when finished:

Except that the area in red will be an 'extension' to the factory slider and not part of the rear bumper.
This new section of slider will be flush against the back of the mud flap, providing an additional anchor point.
I'm not sure yet how far down the flap will go, but just enough to help keep the mud and dirt off of the inside of the rear bumper area.

 

[WestCoastDan]

Here’s a cardboard mock up…
Cardboard is roughly the same size that the mud flap will be.
The slider is too long here and poorly cut, but shows the shape and placement.

 

[Speartip]

Looking good so far

 

[WestCoastDan]

Progress continues.
Mud flaps arrived and i was able to get moderately decent cuts on both ends of the slider section that will be used.
Forget the size of the mud flap and how far it hangs down in the photo, this is only to help finalize the placement of the slider rail, dimensions, cut angles, etc.
Yes, I chose to go with black, diamond plate mud flaps to follow through with the design element that already exists on the hood/cowl corners, door sill guards, and license plate frames.
I'm even hoping that there will be enough material from the mud flaps left over after trimming them down to make matching door handle inserts, but that's only a hope.

 

[Dirty Dog]

Are you going to bevel the trailing edge to mate up to the rear bumper? What about spraying bedliner on the assembly to match the texture?