As the original bracket is fixed in Z axis and I wanted it to be rotatable, I designed a bracket to be plugged on a 12mm stainless steel pipe I welded on the windscreen frame.
The bracket can be printed on a MK3s - need to rotate it ~45deg and place it exactly - but it works ;-).
Print with temperature resistant and strong material, ideally some enforced PA. Don't need supports.
The spacer and the bracket have rips to prevent unwanted rotation by the boats movement. Maybe use some glue to fix the spacer on the pipe.
I welded a M5 nut into the pipe, so all can be fixed with a wing screw.
The author marked this model as their own original creation.