I did a similar loop a couple weeks ago and was 14 miles from Ashland. I started in Park Falls and went north (14 miles from Ashland) and over and then down though Clam Lake back to Park Falls. It was 170 miles and took 6 hours with minimal stops and fueled twice. The route you are talking about is likely 50-80 miles further so add another 2-3 hours. Of course this is just a guess.
The route you are taking, from Park Falls would be only 65 miles to Hurley, just a bit shorted from Butternut.