My preference is to avoid rail trails and other bike trails in favor of regular roads. I have crossed Kansas a couple times as part of a longer tour and found it a nice place to tour. You can find a place to camp in most small towns, usually in the town park. I recall only one small town park in Kansas (Satanta) where I was not allowed to camp in the town park but asking around got me an invite to camp at a local church. I typically never managed to get actually permission, but usually asked at the general store or minimart, "Do you think anyone will run me off if I pitch a tent for the night in the park". If the town is large enough to have cops, I usually ask them.

The people are usually exceedingly nice in Kansas. The scenery is a bit boring for most of the state, although the Flint Hills were pretty at least in the Spring when I was there.