So it came to me. I'd just re-attach most of that piece of fender back on without the tail light mount. This would give me a shorter than stock fender, a place for the plate and practical water protection.
Thats the nice thing about not having a solid plan when doing a project like this. If I feel like changing it then thats fine.
The first step was to remove the factory tail light mount.
I cut it out with my favorite tool, the Milwaukee 18 volt grinder with a cut-off wheel. That piece of steel is a heavy metal shelf I rescued from the dumpster at work.
Cut, pound, weld, sand and paint. I left that pointy flare on it. I figured it would be easier to make it look halfway decent if I wasn't trying to blend a seam together.
I can live with this. Its not as long as the stock fender but plenty long to keep me and my gear dry. The plate location works with the rack folded down and should keep Johnny Law off my back.