My roughly 2 acre pond required moving just over 70,000 cubic yards of dirt an average distance of 800 feet. The slip scoop I had was made by Ferguson and the old tag on it said 1/10 cubic yard. So, based on your earlier calculations, a guy would move closer to 3.5 cubic yards of dirt in a long day. Assuming no bad weather, that would take about 20,000 days of work (bad weather would slow production during that day). At that rate, if a guy worked 8 hours per day, 7 days a week, 52 weeks per year and never took off any, he'd finish the pond I have in about 55 years. Remember, that doesn't count the grading work done with the 70,000 cubic yards of dirt moved either. That would take another few years of work.
Also, as all along, being realistic, one tractor would likely not be up for the task; especially without being able to miss a single day of work. To make any progress at all in digging a ditch with the one I had, I had to plow the area to be scooped first. I still have the old plow. It's a 2 bottom 14" plow and I was using my father in law's 8n tractor at the time.
When I got serious and dug my pond with the appropriate equipment, without any doubt, 1 full square yard of the heavy clay soil weighed right at 3000 pounds. If you could fit a 1 yard scoop on an 8n, I just can't imagine it being able to handle that weight either. Once into the wet clay, I'd say that much weight would get the tractor stuck every load, destroy the hydraulics on the tractor and get a guy dizzy running circles around the pond trying to climb out since power would also be an issue.
As I've said all along; most anything is possible. However, using the correct tool for the job makes all the difference in the world. So, yes, technically if a fella had a fleet of tractors, he could dig my pond in about one full lifetime. Again, being realistic, I seriously doubt any guy would spend his entire life digging a pond. He'd have no life, no family, have to be independently rich (not able to work and have to keep fixing tractors and buying replacement tractors) and one healthy fella. If that's your sole mission in life, have at it. Be sure to post pictures of all the progress.