A New 2 1/2" wide section was made and the corners shaped from the existing Lid corners
A Right Angle fold 1 1/4" deep finishes the Panel.

Here we see the Panel tack welded from the inside onto the existing Right Angle fold.
The Corners will be filled in in due course.

All Done, we can now trial fit the Lid and start on the bottom end including the Beaver Panel.