Do you think the frame rail is thick enough in that area? Seems like maybe a 1/4" plate einforcement welded there wouldn't be a bad idea....maybe 8" long or so as wide as the frame rail.
My cars are 100% from So Cal,, factory undercoated, and don't have any frame rust or even surfact rust. I used to have one in my Barracuda for 16 years, 80K miles. The Dart has about 20K miles on this one.
But I heard of them pulling through.
Now, if you install them with the end link not totally perpendicular to the sway bar and the mount at ride height, that will load that mount all the time. I had to cut the end link to right length to get that right. Also use a washer just wide enought to cover the poly bushing that goes into the frame mount. It's super tight and the washer can rub things in there. It's takes a lot of effort and patience to get the end link right, IMHO.
I think a combination of rust and install together cause the pulling though.