I lived in Joplin, Mo and currently have a cabin around Lebanon, Mo.
Mo, has very stable soils, you have solid bedrock very near the surface of the earth. Many of rural homes have used just this idea for a foundation. Finding the right rocks and the proper mixed mortar and digging down a few inches to bedrock will insure you a very stable foundation for your project.
I would do this first, dig down to bedrock, then make a square form from 2x8's, then with concrete and rebar make you a platform for the rock foundation to sit on then build up about 3 feet.