If the salt is seeping in, the moisture is too. Seem sealer would help, but only if you can wash and dry the top good enough first. Since it's not leaking I personally would wait until spring when you can really wash it down good and let it dry in the sun.
2013 JKU Sport, billet, auto, 3.73, LSD, 315/75/16 Duratracs on MB 72, 10A springs, Bushwacker flatties
Sold - 2005 TJ, red, auto, 3.73, 33" Duratracs, 4" lift
Ice storm casualty in 2007 - 2003 TJ, green, auto, 3.73, 33" Duratracs, 4" lift