I learned from the head sales guy that the back hoe should be only the size which the tractor's hydro pump can work.
Also I do most of the work w/ the 9 inch bucket (3 teeth). Our 18 inch bucket is used for digging sand.
The massive roots under some of these old trees have to be picket at nearly one at a time.
I have learned that some old pine trees will drop several tap roots right along side the main tap.
Some of the secondary tap roots went down & easy 6 ft. When you start on one of these old buggers you're usually there digging, cutting & pulling out to locate the main big anchor.