how to install flagstone in hard rocky ground
 

I have a newly purchased lakeside cottage in maine. Tiny place but it works for us. The lawn from door to lake has worn away and I want to install flagstone type pavers. Loosening the surface soil to set the stones at ground level is not viable. Rocks and roots everywhere. I am thinking of dumping a couple inches of peas stone on the ground and setting the pavers in this friendly material. But I am concerned that this gravel may tend to travel and I cannot easily contain it. Any suggestions? Thanks