If you are looking for some singletrack to camp near, Blue Mound is your place.
If doubletrack, well Blue Mound is still your place. Military Ridge Trail runs right past it, and you can camp in the special bike camping area right near the trail. Also has nice facilities if you want them like showers, and even a really nice pool
I have found the combination of riding, with breaks for the pool, make for pretty happy kiddos