Okay, Point 1: Hydraulic lift systems have high pressure bypass valves built into them. The bypass valve will not the let the tractor lift anything heavy enough to break the lift mechanism.
Point two: lifting 1200 pounds centered 12 inches behind the rear tires is not the same as lifting 1200 pounds centered 36 inches behind the rear tires.
Point three: A disc is fairly heavy and the weight is far behind the drive axle. When lifted into transport mode. It can, in some cases, cause the steer tires to lift and float. It looks like your tractor is equipped with a front end loader. That should be enough weight to keep the front end on the ground. If it wants to float, put some rock or sand in the bucket.
Point four:Tractors have, since 1960 anyway, a traction/lift control adjustment. As the tractor senses increased work load on the lift arms, it will add pressure to the hydraulic lift mechanism which has the dual effect of transferring weight to the drive axle which increases traction, and also lifts the implement out of the ground which decreases load.
Learn where this adjustment is on your tractor and tune it to balance the amount of work/pull against the amount of lift relief. That is what it is there for.
Set it to light and your implement will just scratch the surface. Set it to heavy, and the tractor will bury the disc in soft ground and spin out.
Also, find out if your tractor has a differential lock. Step on the diff lock and lock the two rear wheels together if one tire starts to spin.
