Myself, I would not force the writing during the summer if he hates to write. If social skills are priority 1, I'd put my focus there, with lots of practice opportunity, debriefings where relevant, and just generally conversation about what's going on in these new experiences.
If I tried any kind of journaling plan with my DS12, it would devolve into a great deal of aggravation for all parties.
If your DS is willing, then go for it. But if not, and it's not priority one at this point, pick your battles.
