I've completed repairing a couple more rust spots. The first is the lower front portion of the driver's side rear wheel well. Here's the area prepped for welding:
Here's the replacement piece ready to go in - it's not quite identical to factory, but it isn't goiing to be seen and it lines up, so good enough!
And here's the area after the replacement was welded into place. This ties together the previous repairs to the inner and outer rocker panels as well as the quarter panel patch between the door and wheel well - it was a big relief to have everything line up properly:
That left a small piece of the floorboards just ahead of the rear wheel well to be fixed:
And here's the rear of the car's rust repairs completed: