I cut the window out.
It felt really weird to be cutting out a section of perfectly good metal that was going to be welded back in again, but it had to be done.
And the nice big hole.
I had to be careful as just above this cutout is a seam of the hinge pocket which is welded on this inner panel. The seam isn't fully welded and has at least two areas I can see that are designed to let water weep through. So when I weld this panel back in I have to make these welds decently smooth to keep water from catching on them.