Your fix looks good! I'll be fixing some rust holes in the D/S rear wheel well in the near future. My rust isn't as extensive as yours, but if it was I would be tempted to cut this rear of the wheel opening just under the tail light and then weld in a new part to close up the bottom. Just what I would do with my own rig. As I said your fix looks like it turned out realy nice. Congrats!!