Don’t know about muddying in placer county, California’s not the most friendly place in the world to enjoy the outdoors without breaking some environmental commandment.
Forresthill rd off highway 80 near Placerville leads to a lot of logging roads in the winter are pretty muddy and covered in snow. Pretty country and lots to explore. Deadwood rd off of Forrest hill rd winds back to the old ghost town of Deadwood and old mining town all that remains is the cemetery. But you will find miles of dirt roads to explore.
the link is for directions to hiking but gives directions to the logging roads that lead to the hiking trails.
https://www.fs.usda.gov/recarea/tahoe/recreation/camping-cabins/recarea/?recid=75363&actid=50
there’s restrictions probably about getting off the established dirt roads and the logging company’s might not be to happy if things get torn up but if you just want to explore beautiful country there is a lot of logging roads that lead off the main forresthill rd in that area. Pretty easy to get turned around and get lost so bring your bread crumbs.
Depending on the snow conditions the road may or may not be open so call the forest service first.