you can rent mini ex (mini excavators) fairly cheap.
for basement digging, large size industrial units, most likely needed. or less ya digging into a hile side.
for one time usage, just call up a local excavation company to dig it, and be done with it. thats there day job, and have larger machinery and other trucks to move the dirt around the area, or haul the excess dirt away.
as others have already said, most tractors already get biggest backhoe that can fit on them. the further you reach them out, the more likely the front end will come off the ground. most TLB (tractor loader backhoes) have a FEL (front end loader) to extend weight further out in front to counter act the weight from the backhoe and how far it can reach out.
think a kids playground (tetter totter)
you can only add so much weight, and how far it sticks out in front of the tractor before, things start bending / busting / cracking. (from tires themselves to axles to simply the frame of tractor twisting)