I think it will be helpful to you both if you really drill down on a specific recruiting plan and target school list with more definitive rationale. Part of the process, one of many steps is gaining a good understanding of the realistic issues and costs regarding the in-state/out-of-state thing as previously mentioned. Perhaps he can just share with the D1 offer school that he wasn't prepared to make a decision in that timeframe and ask for a bit more time. Meanwhile, also compile a list of questions for that school that will both better inform you and show mutual interest, while not committing when he isn't ready to do so. Of course, the downside is that most D1 schools have a decent size pool of mid-80's RHPs to choose from to offer, so you may not get much of an extension.