Buck, obviously I'm unable to answer your question re: the location of a sling type launch in Virginia (since I'm in Washington State), however the following info may help you.
At the conclusion of washing my boat and trailer after a "dip" in salt water, I spray a product called "Salt Away" on the brakes. (I also use salt away to flush the engines).
Once in a while a person will find launch ramps that have hose bibs conveniently placed where you can hose your trailer off after launching your boat and again rinsing your boat and trailer after the retreival process and even flushing your engines before dragging your rig home. Whenever I find a launch ramp facility that provides that "special touch", I definitely use it. (It gets rid of that salt water crud before it dries!)