Us Too
We had this problem too but, while visiting Toronto (where we also got the ChipGuard on the full front and the rocker panels) and driving in a lot of salt decided to have the baby sprayed by Krown Rust Proofing.
Not sure what this foamy pink stuff is. They call it a "chassis lubricant" and "rustproofing" that virtually eliminated the chassis noises our truck had. This Krown stuff also seems to have either covered up or washed off the white stuff caused by the salt. The surfaces are not as smooth as before the salt but this stuff does work as we had our Ford Lightning done twice up there on alternating years and never had the bad chassis noises the Fords are known for after the first treatment and NO rust after four winters (sold it to a friend last fall when the SSr showed up).
Found out about Krown through a friend in the Jaguar Club in Toronto who has a concours XKE and has this car done bi-annually. Also, the mechanics really seem to like it as it keeps the nuts and bolts very easy to take off and is not sticky/waxy like some of the other products. The XKE is in fabulous shape and the buddy credits the Krown product. Cost was like less than US$100 each time and my feeling, based on the Lightning experience, is more than positive.
:seeya