I have beet juice in the rear tires for ballast and I have an 87" 3 point blower that goes around 1200 lbs. I am mostly concerned about being able to steer the blade. The tractor is 4wd and I haven't considered chains for the rear because there is little clearance between the tires and the fenders. I am going to set up the skid steer plate with a short boom that suspends the blade with a chain, like it was on the truck, it will then float.
Check your owners manual. Many tractors in that size class have multi position rims that let you adjust the tread width which also changes fender clearance.I haven't considered chains for the rear because there is little clearance between the tires and the fenders.
Could you make a sub frame to mount the plow to? I have an International dump truck with a 10' plow. A few years back I caught the edge of the plow on something frozen to the ground as I was trying to push the banks back a bit. I was doing at least 10 mph trying to get the snow to roll off the blade and carry some speed into the woods. The truck stopped dead and bent one of the angle cylinders (which are large) and the frame on the plow. The trip springs did nothing to prevent the damage. Plowing at speed means you have lots of momentum and something has to give. The loader arms seam like the weak link to me.