The drawbar towing capacity for the Kubota M6040 and M7040 are the same - 11,000 pounds. The towing capacity of your T4.75 should compare favorably with the Kubota M7040.
I agree - the max tongue weight for the M6040 & M7040 is 2200 pounds. I wish the Tractor Data site showed tongue wt and towing capacity - but they do not. Maybe someone with a T4.75 Op manual will pop in soon.