Welding rusted metal is a miserable job, and doesn't make sense when you are trying to get rid of rust, so don't be shy and cut at least a half inch into good steel to avoid chasing an ugly weld into rusty metal later. | 
Another hammer formed part is used to duplicate the original geometry. | 
Due to the geometry, a combination of lap, butt, and plug welds are used here. A coat of self-etching primer and paint will take care of the interior. |
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Trying to close the hole with one big piece was probably a bit ambitious, as I ended up have to hammer several features and bends into the part; cutting into two smaller parts would have made the job go easier. | 
The hinge support structure is replaced with 16-gauge steel, just as original. |
This part was made before I discovered shrinkers and stretchers--and it suffers for it, but is still a structurally sound fix. | 
Again, breaking the puzzle into smaller parts. | 
Closing up the rocker panel I attempted to add a couple of ribbed features like the factory had done using basic hammer forming techniques. |
After fitting the fender back on, a hole will be added with a corresponding nut welded to it to duplicate the factory fender mounting. | | |