Hey folks, I’ve got this area rusted through on both the driver and passenger side of my truck. This photo is the drivers side. It’s just behind the lower front corner of the front door.

It seems to be a separate “layer” of sheet metal that curves up and to the right in this photo. Everything surrounding it is a different layer of metal and is all solid. It’s just this layer that rusted through. I’m wondering what is the best way to repair it?