Here is a website listing 29 Minnesota Sate Parks which have wheelchair accessible trails. The site also lists accessible campsites and/or lodging. The trail descriptions are minimal and if there is more than one in a park, only the total mileage is given.
If you have Minnesota disability license plates or a rear-view mirror hang tag, or if you have a Federal Access Pass, you can get a reduced rate special annual vehicle permit with proof of disability and proof of vehicle ownership.