I ran a 140 Suzuki on my 18' Duckworth and that boat was used in salt all the time. After every use in salt I would take the boat to the lake and run the main and kicker until they were both back up to temp. The idea was to bring the metal back up to temp to open the poors in the material and that way all of the salt particles would be flushed out. I do the same now with my inboard 350 Chevy, no matter how late it is getting I always take the time to flush the main and kicker at the lake. This will also help with getting some of the salt off the trailer too. I have done this technique for years and have never had a salt problem.