What have other people in baseball (travel coach, high school coach, scouts, college coaches, any people you trust) said about your son's skill level? From your post it appears he can do a lot of different things....switch hit, switch pitch, play multiple positions but what does he do extremely well or what is the specific skillset that is going to take him to the next level that is going to grab a coaches attention? Being devil's advocate....why not just go straight to JUCO, and start his education and development w/o the NCAA 5-year clock ticking?
Chasing the dream is great, but I think it needs to be somewhat realistic and a path clearly defined. I understand you are just kicking the gap post grad idea around based on the offers your son has received. What is it about those offers that is leading you to consider the gap post grad idea. You said the offers were okay not great. Clearly these offers did not meet you/your son's expectations. Specifically, what are those expectations? I just think you need to back up a little bit before heading down the rabbit hole.
As always, JMO.