If you want more gravel try the walk option on Google Maps. The bike option keeps you on paved roads/paths. Of course walk is also the shortest distance and you may not want that.
Google maps is a great place to start looking for directions, but I find that I always have to make a few changes to do just what I want. I use the Delorme state atlases or better yet Sportsman's atlases that use DOT maps and show campgrounds, natural areas, and bike trails...even in the corn belt.