[GuyO]

It sucks but where there is water and oxygen, theres rust. And like Frank says, just add salt and the sodium chloride makes it worse especially if the water can't get out like where your area is. Personally, I do not think there are enough drain holes in Burbs or Blazers. Even with Pickups, the fender and door drains are too small and get plugged with dirt or spray on undercoatings. I too would cut it out and weld in a new piece but be careful welding a galvanized patch, heating the zinc becomes a poisonous fume. I have tried a lot of things for rust removal and rust treatment including electrolysis using laundry soda, muriatic acid dips and occillic acid dips for parts. But for body grinding/brushing/neutralizing and patch panels! Good luck, love Burbs! G.