Salt Away will be your best friend and will need to be used on everything. If you have a tube trailer, take it and get everything sealed up with a shrader valve to pressurize the tubes while you launch and retrieve. If you are diligent, you will only see the ill affects on the trailer after several launches, rather than after the first launch. The boat will not see many ill-affects immediately, but typically the steering cables and everything metal will show corrosion after a several uses. The biggest problem I have seen on the boats are when people get into the boat dripping wet with salt water and get the interior soaked.
A Saltwater skiboat would be sweet. I'd build it so there was not a thing in it that could not be sprayed down and wiped off or removed completely.
However, my salt skiboat is a $2,500 outboard and the MC stays at the fresh stuff.