Hey I just moved from Ames to Missoula, MT. We did a short tour in Iowa but it was to NE Iowa. Once you get further west there are more campgrounds as well as free camping in public lands (usually). I second the crazyguyonabike journals which are really helpful. If you choose one of the Adventure Cycling routes at least people are more used to seeing touring cyclists but I don't think any would line up with your route without adding a lot of extra traveling.