We had a few different design stone boats over the years. The last one we made was hinged in the middle at the back. We would open the hinge, place the stone boat sides around the rock and then pull the stone boat with a chain rigged to "pinch" the rock and squeeze it up on top of the stone boat when the two halves came together. Worked pretty good on medium size rocks.
I used the point of the angled blade on the road grader to lift the rocks on top of the ground so they could be loaded onto the stone boat. On the larger rocks, we used the HD7 and dozer - except that there are some that even a D8 can't move.