Metcalfe Farms used to use a ramp for loading the mixer,it was a right balls because the clamps were long an low so they driving a huge distance to fill the mixer.Get a Cat 966 with joystick steering and custom buckrake. let the trailers come at you in the pit . Might need to make some yards a bit bigger but be a decent outfit.
On a more serious note, as has been said get a decent quarry brand shovel with long arm. Then build a loading ramp or platform for the feeder.