Turned up a pair of spacers & extension bars, cut & folded some 3mm alloy sheet to form a 'backing' bar.
Made the external cover, but didn't like it so did a second, this looks a bit better, sprayed it 2-pack silver & PU bonded it together, & bolted it up.
Made a logo & stuck it on. Although it does have bit of a radius, I still feel its too straight, & not too sure at the moment as to the look, I might
make up a pair of handed 'infill' panels since the little panniers are short at the rear.
Also have to turn a couple of shiny 'bullet' nuts to tart it up a bit!