I did it a couple of years ago. It was a lot of fun. I don't live in Fond du Lac anymore or I'd probably be doing it tomorrow. I'm about an hour and a half away now. I will probably do it again next year but I've had other stuff going on the last two years. Good luck on your goal - under 4 hours is pretty impressive. If I remember correctly, my cousin's husband did it in 3:48, something like 23.6 mph average. I finished in 4:54. The first half was a breeze as I was able to stay attached to a fast pack (24-28 mph with surges over 30) but I had terrible cramping the second half. I think I was in a little over my head in that fast group.