Assuming that you are referring to protection from corrosion from the salt air, I can tell you what we, as Canadians, do to protect our vehicles from corrosion from the salt that is spread on the roads to melt ice in the winter.
First, I get the truck sprayed with a type of drip-less oil (looks almost like Vaseline). The stuff is sprayed under all fenders, inside all doors and the engine compartment. For example, see Antirouille Barry's Rustproofing
who does this in Montreal. As well, I had an electronic module that is a form of sacrificial anode installed on the truck - see CounterAct Electronic Rust Protection System | Canadian Tire
Exterior surfaces should be waxed. I got a can of the undercoating spray Rust Check Coat & Protect | Canadian Tire
to spray under the trailer where there are exposed metal.
You will also need to hose off the truck and trailer from time to time to wash off the salt that the mist deposits.
Let's see what others say.