Building Disk Harrow for the Garden Tractor

I'm putting together a disk harrow for the Garden Tractor. I pick up these disks last fall cheap. I believe they are from and old David Bradley walk behind tractor. They are 12" in diameter. I will mount them on a steel bar with clasps. I want to be able to adjust the angle of the disks from +20 to -20 degrees. It will be 38" wide to match the width if the tractor. I will build a tonge and hitch to fit a standard garden tractor sleeve hitch. I want to make the tonge long enough that it will follow the tractor through the sharpest turns without making contact with the rear tires. This will also make it possible to be pulled with a ATV as well. Most small harrows need extra weight to dig. I'll make a tray on top so weight like cement blocks can be used. Well time to get busy. AH