You might also get in touch with the local cycling associations for each state and see if they have cycling maps for free or for sale. Several years ago Alberta produced a cycling map which I still refer to. It colors the roads different colors to indicate traffic density, and also indicates things like shoulder width, pavement, etc. Using a map like that, a cyclist could pick and choose good roads - wide shoulders, low traffic density etc. The city of Edmonton has also put together one for the city ... good options for getting through the city.
Manitoba has one for the city of Winnipeg, and then they sell a book which tells you all the good roads for cycling and which ones to avoid as well as other tips like places to see, where campgrounds and other services are, etc.
I can get ahold of all of that through the cycling associations of Alberta and Manitoba ... so perhaps you might be able to get ahold of the same sort of thing down there.