Same issue here. I just finished constructing a hydraulic auger for post hole digging. ! pin and 2 hoses. done. I use the bucket curl circuit to run the motor. And it's bi-directional.
I park the bucket fully curled down so that there is no preload pressure on the cylinders or disconnects, but stays locked in place. The motor, hinged cage and hose are 1/3 the weight of the rear geared digger. I can drop the bucket or lift the motor to get it mounted. Used a trailer drop hitch on it's side in a standard receiver to handle the hinge. Raise the loader, plop the auger on and insert a 1" pin. Connect the hoses and we are done. I have it off to the side of the bucket so I can drop the auger tip on a dime if necessary. Nice for placing a new post right next to a broken one.
Cost was $38 for a 1" to 2" connector from Graingers. 1" shaft of the hydraulic motor and 2" inside dimension for the auger(s). Drilled out the Allen set screw on the 2" end and ran the hole all the way thru to hold the auger in place.
Works like a charm. I use Left/right (curl circuit) to drill and fwd/bkwd in float on the joystick to get up and down. The motor was a garage sale find, turns about 100 rpm at idle on a 8.5 gal/min tractor's pump. No gear reduction or extra material onboard. The motor cage was all rigged from scrapped steel plates from curbside garage door opener spring support. I even threw some paint on it.
Local Bobcat dealer wanted $1800 just for the motor with a planetary gear set (sold as a LandPride model). No hoses or connectors. It also has a hex drive shaft which means you need a converter connector or buy their auger for $500 (10 inch).
Either way, no more PITA from a rear mounted one, no more hernias, and no more twisted neck strain. Heck, I could hang in on a wall hook for storage if necessary. I can get some pics if anybody wants to think out of the box. What WAS funny in my search for a better system, was how some manufacturers add a hydraulic motor to the gearbox pinion of a conventional digger. OK, no more driveshaft and no more having to move your drawbar off to the side. (I actually fell for that one once). Still heavy, still rear operation, and still clumsy. BTW: mine is self balancing, no need for extra offset weights to keep it straight. I can dig on hills, too. Gravity is your friend !