Most trails in NJ are pretty easy. There are a lot of very easy trails down in Wharton that I'm sure your kids would get a kick out of. Most of the deep water in Wharton have go arounds so you can keep mostly dry (Maybe a little muddy).
There are a couple of guys on this forum that go up to Stokes fairly often, I'm sure one or more of them will chime in on your question.
Good luck with your new Jeep and have fun (thats what Jeeps are for).