Off 30th south of 142nd near dorr there are a lot of seasonal roads that can be plenty of fun. Used to an area near burlingame right after it turned into 16th in allegan that had a network of trails and seasonal roads, nothing major but a fun couple of hours.
There are some power lines that are actually roads, really need to dig into maps to figure out which ones they are. The power line that runs towards long lake park on 17 mile in Sparta then up past 22 mile used to have seasonal road signs on it, but not at the intersections.