How about this? Take the Mississippi River Trail along US Hwy. 61 to St. Paul, then the Gateway State Trail to Stillwater. At Stillwater, you can pick up the ACA's Northern Tier Route to Grand Rapids. (The Northern Tier is all mapped and available from the ACA.) From there you can head north on Hwy 38 and 6 to US Hwy 75 and follow it right into International Falls. That will take you from bottom to top, and you'll see a lot of beautiful country along the way. I can't speak for the part from Reno to St. Paul, but the Gateway Trail is off-highway and the route north of Stillwater, as mapped by ACA, is on low volume roads. Hwy 38 and 6 through the Chippewa National Forest, are fairly low volume but may be busy on weekends. Not sure about US 75.
An alternative would be to figure out a route to link together a number of the state trails, and stay off highway as much as possible. (Go to www.mndnr.gov
for more info.)