Get a tank bag with a big map pocket, print out your turns and miles between each, use your odometer/trip meter to know when you're getting close to a turn.
You could also consider using route charts/roll charts.
To find backroads, I've usually used the "avoid highways" checkbox to get me started.
9 states left to ride:
WI, MN, ND, SD, UT, OK, KS, AK, and HI.