If the 2 track you are on is not designated as an ORV Route and is not passable in 2wd, turn around and go a different way. An ORV tag (actually 2 now) on a Jeep or truck is only to gain admission to a handful of places in MI (Silver Lake, St Helen Motorsport area, Bull Gap) plus one ORV Route (Drummond Island) that has sections that ORV sticker is required. An ORV permit does not allow you to operate your Jeep on an otherwise impassable 2 track or county road.
A forest road is any road in the state forest that is passable in 2wd, and is open to any vehicle with a SOS license plate. A forest road does not require an ORV sticker. A county seasonal road does not require an ORV sticker. If an ORV Route or Trail runs along a road or 2 track that otherwise meets the definition of a forest road you are not required to have an ORV sticker. These rules are not new, the only thing new is 2 sticker system, and of course the cost.
A good map is a good place to start - if you use a GPS I would recommend the maps produced by VV Mapping, he has some of the best maps around particularly of the ORV system in MI. Paper Maps like the Gazeteer are also fairly reliable at showing you where the boundaries for the state forests are, but are generally not accurate enough to identify where private land starts and stops, you need county platt maps for that.