When you say "off roading", are you talking about ATV/ dirt bike riding, or taking a jeep or truck off road?
If you want to ride ATVs,
The Dead Horse Run trail which has a trailhead in Clam Lake is a lot of fun, may be a bit challenging for novices. You can camp at
Day Lake Campground and ride directly to the trail. It is rustic, no hookups.
Park Falls Wi or Phillips Wi offers the
Flambeau Trail and the
Tuscobia Trail and
Sailor Lake Campground or
several other campgrounds, some on the water with direct trail access.
If you are talking about taking a jeep or similar, I don't know of anything "off road", per se, but a lot of the fire roads in the Chequamegon NF are really little more than dirt tracks, some with dirt track logging roads leading off into the forest that you can explore if you are adventurous.
Black Lake campground, google map
here is off the beaten path, about 25 years ago my husband and I saw a cougar up here. Lots of logging roads in this area.