If you already have a sled and want to run in the salt Don't worry about running it in salt as long as you rinse it in fresh water afterwards. as you should any boat prop or pump. I run my sled mostly in the river but do enjoy crabbing and fishing the salt once in a while. I have never had a problem with any corrosion but I do have zinc on the main motor and kicker. I would watch the weather as rough weather and sleds make for a nasty ride but as stated before in a low tide, launching and putting back on the trailer is a lot easier with a sled as you can motor up the trailer instead of winching.
Anyway go out and have fun and catch the big one!
Ramprat