Oh my! Google Maps everywhere!!
What ever happened to using other sources - more reliable sources?
Google Maps is big - but than again, so was the Titanic.

Nearly every state posts online traffic volume maps and detailed county road maps.
Unfortunately, many state are now going to online data maps which preclude a general overview.
(Technology is not always helpful when the result is the loss of the big picture.)

Here is the fixed Kansas Traffic Volume Map -
http://www.ksdot.org/Assets/wwwksdot...untmap2016.pdf

What's nice about a map such as this is that you can spot good routes easily.
Since you want to stay under 2000 AADT - ideally under 1000 AADT - you look for the gray and purple.
Obviously the western part of Kansas has less traffic - but you can find the best possible routes.
(These are US and state highways - there are regional maps which include county roads.)
Notice how Highway 18 has much less traffic than most other E-W routes in central Kansas.

Kentucky has good county traffic volume maps, but not a statewide map -
Traffic Counts

Tennessee has county maps and traffic data but it is in a terrible format.

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Than, perhaps, you can use Google Streetview to see road conditions / shoulders etc.