Tom,
Matt beat me to it. Bates did over 90% of the work according to my source. I've heard about others having responsibility for course construction, but just don't know whether its fact or fiction. Lots of fiction takes place in that Barn/Clubhouse!
Matt,
Hate to nitpick, but although the Colt's Neck area does have quite a few throughbred horse farms, the real "Horse Country" of NJ is centered around Central New Jersey, specifically Somerset County. The difference is actually interesting. The area around and near DP is very flat, low-lying, and subject to periodic flash-flooding. It is also has significantly sandier soil than Central or Western NJ. It is also throughbred race horse training ground, unlike the real "horse country" of Central Jersey. There, the equine set centers around jumping, showing, fox-hunting and more exposure to public riding throughout the local area parks. The USET shares land with Hamilton Farm GC and riders are often seen on the lands abutting the new Trump National site. Somerset Hills also has riders up through some of it's adjacent woods. The soil is more rocky, woodsy and far less sandy than the Mercer county areas. Also, significant elevation exists in and around the real "horse country."
Yours Truly,
Mr. Ed