Good suggestions from Todd.
Detailed maps of the Ice Age Trail are available at your local REI or even Barnes and Noble, or you can order them from www.iceagetrail.org (http://www.iceagetrail.org). Backpacking opportunities in the Ice Age Trail are primarily confined to the two main units (South and North) of the Kettle Moraine SF and to areas of the trail in northern Wisconsin, primarily this would be Langlade, Lincoln, Taylor, and Chippewa Counties. For the North Country Trail in WI you can order maps from them and also see http://www.northcountrytrail.org/htg/guides.htm for some guides for the longer stretch which is mostly in Ashland and Bayfield Cos. though there are also shorter opportunities in Douglas Co.
Nicolet area (which is northeastern Wisconsin in Vilas, Oneida, Forest, Florence, Langlade, and Oconto Counties) has some backpacking opportunities, but I'd recommend you call the USFS and ask for a trail guide which they would send you for free. However, they would not be that long distance unless you were to do some kind of off-trail route so that's probably not what you want.
You can email me at
[email protected] as I don't check this site all that often.