David
You are talking about adding stanchions. Your boat was initially designed with out stanchions. They were added based on public opinion and desired safety. You can add a single about 3 feet from an existing stanchion on the side of your boat.
This will require changing the lengths of the wires presently in place. Because it is a gate you need to have a brace on the stanchions. You can make the gate an easy hold by making it out of 3/8 dyneema. I did that on my boat and it is an excellent system.