-- Last Updated: Mar-04-13 8:57 PM EST --
I just looked at air photos of that whole stretch, and it doesn't look practical. Not until 5-Mile Road do I see reasonable stretches that aren't nearly completely choked by trees. Upstream from there, which is most of the trip, the river is totally invisible beneath the trees more often than not. Photo sections taken in fall/winter/spring, when visibility is better, show lots of deadfall tangles. As you approach the reservoir near Racine it opens up, but below the dam it looks awfully shallow for quite a stretch, again often nearly hidden by trees. I'm surprised you didn't see deadfall blockages from some of those bridges. Most rivers that I'm familiar with that look like this from the air have the "look" of being deadfall-choked as seen from road bridges too. Did you try to look very far upstream and downstream from the bridges?
I'd suggest taking a walk through the Root River Parkway, both upstream and downstream of 7 Mile Road. That section of the river is noticeably wider than the stretch where you want to start, but still looks like it's probably a tangled mess of fallen trees unless some dedicated group has been busy in there with chain saws, keeping a path clear. I could be wrong, but that's how it looks in the photos.