I am trying to figure out the best way to approach rust repair on my wagon. The car is actually fairly rust free, except for at the bottom of the rear side glass. it is not rotted through, but it it is pitted and seems to be rusted between two panels that are spot welded together. I was thinking of sand blasting the area and treating it with POR-15 or something like it. The only other way I can imaine would be to cut the two seamed togeter pieces out and replace them. I can get to both sides of the seam that is rusted, but I don't know about in between the two pieces of metal?? I think I will keep the car for a long time so I hope to do something that will last. Any suguestions would be appreciated.

I've heard good things about the POR Putty patch.
It dries like steel.
Sounds like it may be the best remedy.