Landing in a flooded salt marsh is just about the most corrosive and detrimental environment possible and if this is a land plane or even if it is a float plane I would find another flying site.

Many of the normal recomended techniques such as bagging rx's is actually detrimental and will add to problems, the bags do a wonderful job of holding water in and are terrible at keeping it out. Have flown floats for years in fresh water including many imersions with no issues but I avoid salt water.

Also there is no Rx you can buy that is not going to be affected by salt water immersion.

John