It is good to see a few cheeseheads on here! I live in Madison as well ad love the **** out of the rail trails here in southern Wi. This summer I tried the Cheese Country for the first time and was also defeated. My plan was the Badger trail to Monroe, then Cheese Country to Darlington. After that roads to Potosi, the up the Miss. river to LaCrosse, then the rail back to Reedsburg and roads to Madison. I bailed the Cheese country after about 10 miles, then took roads to Darlington. I have a Co-Motion Pangea with Conti Top Contact - 26 x 1.9 inch. I want to do part of the trans wi next summer, and am in the same boat as you. I can't afford a new bike so I think I am going to try the biggest tires I can fit and see if that works in the sand. I think the biggest I can go and keep my fenders is 2.1 inch, I don't know if that will be enough. keep us posted with your choice, I would love to hear how fat-bikes work on some of Wisconsin's ATV trails.