Our grandson got back from Afghanistan 8 weeks ago and we stayed at Willow Pond on Dix. They had a dump site, water and 30A service, but with current temps, the water is probably off. Their reservation setup is a bit funky as the long termers tend to park where they want and you may be assigned to an occupied site, which is what happened to us. THey finally got it right and we stayed a week while grandson processed back in.
Here's a site to give you more help. http://www.militarycampgrounds.us/new-jersey/willow-pond-camp
Call and see if you'll be able to get on post. A copy of son's deployment orders will probably help. I'm retired military so we got right in without an issue, but you'll need to check with security to find out if you can get on post and what you'll need to present to the gate folks. Plan on arriving daytime weekdays for sure.
The campsites are back in along Willow Pond, but they're great for sending a warrior off or welcoming him home. No standard "campground" amenities.
Good luck and please thank your son for his service.
