Congratulations to your son on being selected. Participating in Ranger Challenge was a catalyst for improvement in Cadet Delahanty's performance in AROTC and at school overall.
The competition is likely to be a grind of 36 or so hours with not much sleep. I don't know about Fort Dix, but the competition is not really geared to accommodate non-military spectators, even if you could get permission from the brigade and the battalion. I know the last thing Cadet Delahanty and his teammates would have wanted at the end of a long ruck march would have been me and Mrs. Delahanty exhorting them to hurry.