Can your son hit? I've seen my share of outstanding defensive catchers in high school and college. All three of my boys were primarily pitchers in high school but also played the field and hit. In college, nothing separates a catcher from another catcher like being able to hit. Switch hitting catcher...double bonus. IMHO catcher is THE most important position on the field. He always needs to know what is going on in both dugouts, be a step ahead, and get a feel for the flow of the game. If he can add anything to the offense then you have a rare skill set of offense, defense and leadership.
PS..You shouldn't have to do anything except support him. He will gravitate to where he wants to go. If your son is a college bound recruited baseball player it will be very apparent what skill set separates him from others, and is in demand with college coaches.
As always, JMO.