Your machine with its loader is only ment to reclaim materials light in weight it is not designed to
what you are trying to do.
Pushing the stone from the side of the pile in six inch slices to make a long windrow is the only
way to do this if you do not want to rent a tracked skid loader like a Toro Dingo.
A couple of square flat shovels with fiber glass handles, a small dump trailer for garden tractors,
good friends, beer and pizza is the only real way to fill the bucket filled by having the bucket fully
retracted and pushed against the pile.
Renting a toro dingo with a bucket will be faster.