My dad moved literally thousands of bales over a 20 plus year period with an 861 Ford Powermaster and Ford FEL with a PTO driven front pump. I think with loaded rears that tractor was around 4500# and worked really well for our bales. At the time we used an old chain baler from New Holland and the bales rarely got over 800#. That combination with a box blade was very stable.
If I was moving 1200# bales I would want a full blown utility tractor over 5K pounds. Compact tractors today have hydraulics that are so much stronger than in years past.