OT NPC Rust help., Trouble in the Swimming Pool Options

[TargaToy]

4 years ago, believed a sales pitch and my wife and I purchased an above-ground pool with a salt water system. Despite my questions to the contrary, the salesman assured me that the pool water would be "less salinic than a human tear" and that corrosion would not be a problem.

He has since "moved on" and the pool store acknowledges that the rep lied to many people. They also say he SHOULD have highlighted the fact that a salt system would void any warranties for the pool. Nice.

I'll get to the question soon.

On top of each post of the pool, there's a "joiner plate" which is made of steel. This plate rusts like crazy. Twice, I popped the caps and coated these things with an Eastwood product but I could only get to the faces...they are rusting everywhere. This year, they are crumbling into the pool.

I've ordered 17 new plates and I'm planning to treat them with the best stuff I can find before installing them. Short of powder-coating, what might I try that will make the parts far more impervious to salt water? I *think* they are galvanized steel as the come from the manufacturer.