I made one to fit on the loader bucket. Wish I had a picture but had heavy angle iron 4 foot long welded perpendicular to the pipe. The top of the angle went over the cutting edge of the bucket. Pipe went under the bucket. Had chain hook welded on the pole about 10-12 foot up from the cutting edge. I used 2 chains to go from the chain hook to a hook welded on each corner of the loader bucket. I used somewhat light 3" pipe cause thats what I had. and could lift 500-600 lbs up to 25 feet with what I had. Used it to set roof trusses on the shop.
I think your asking lot to put a pipe over the bale prick and pick up 1500 pounds. Going to take a large tractor and put lots of stress on the bale spear.