Regarding Routes - -

There are no Adventure Cycling Maps for your specific route - however -
Most of the states have traffic volume data available online.
You can go to each state DOT and find the appropriate maps -
I would plan the route using AAA or Rand McNally paper maps so you can get the "Big Picture"
That's the problem with Mapquest and other online programs -
It's often hard to visualize the larger picture - - yeah there still is a place for paper.
And as Machka says, paper maps fit better in the handlebar bag slot.

MICH - http://www.michigan.gov/mdot/0,1607,...6053--,00.html
IND - http://www.in.gov/dot/div/traffic/count/index.html
ILL - http://www.dot.state.il.us/bikemap/STATE.HTMl
MO - http://www.modot.org/safety/trafficvolumemaps.htm
KANS - http://www.ksdot.org/burTransPlan/ma...rafficdist.asp
OKLA - http://www.okladot.state.ok.us/hqdiv...maps/index.htm
NM - http://nmshtd.state.nm.us/upload/ima...sp?show=County

I would strongly recommend taking the Katy Trail across Missouri.
It is pleasant, car-free, and has bicycle-friendly communities.
http://www.mostateparks.com/katytrail/index.html

That means you have to get to Alton, Illinois
Then hit out for New Mexico from Clinton, Missouri.
Depending on where you want to end up in "northern" NM -
Avoid US 54 everywhere - avoid US 64 from Clayton to Raton, NM
US 56 is pretty good in west Kansas and the Okla panhandle - great in NM
OK 325/NM456/NM72 from Boise City to Raton is super - but there is about 35 miles of hardpack

Feel free to drop me a line -
I've biked many of the routes west of St. Louis.
My cycling in Illinois and Indiana is restricted to the southern parts of those states.

Best - J