OK, please note that the Water Parks and More option is ONLY for Oak Trail.
So I have to ask about what sort of golfer is your DS? If he’s really into it and wants to play every day, this will not do the trick, because Oak Trail is a 9-hole walking course. Most golfers prefer the 18-hole option, so you might want to check on this with him.
All the other courses at WDW are 18-hole and usually can be booked easily. If he is REALLY interested in playing a lot of golf, I HIGHLY recommend seeing if they still offer a golf annual membership, which offers you a discounted rate at any of the courses. I am not sure if this program has been discontinued (I heard rumors that it might end), but it sure pays off when you travel with a golfer!