Some of my Pax brackets needed larger than usual screws because the plugs found historical holes... So I built the original wall bracket, and then I made a modified version which is 5mm taller, covering even 10mm wide screw heads.

You can choose the print orientation but it needs supports either way due to the shape, so I suggest putting the supports on the covered back side, keeping the outside face nicer. Otherwise you can use default settings like: 0.2mm layer height, no brim. Infill doesn't matter, this will be built using just walls.