I agree 14k for a tractor backhoe is excessive. Sorry to hear Woods lacks a subframe for your specific model of tractor. I looked at your picture and those rocks are huge. Love your tractor....I almost got the JD 2038R when I was buying a tractor, but went with the equivalent CK4010SE from Kioti.
My backhoe to answer your question is the Kioti KB2475L. Its an exact copy of the Woods BH75, and is made by Kioti (Daedong) in South Korea just for their CK family of tractors. Kioti and Woods have some kind of business agreements. Kioti also makes a KB2485 backhoe and a KB2465 backhoe for their tractors. Which should now recognize as duplicates of the Woods backhoe models. Also Woods makes the entire implement line for Kioti Tractors. All the Kioti tillers, cutters, mowers, stump grinders etc etc are made by Woods in USA. Just that Kioti manufactures their own backhoe lineup.
KIOTI Backhoes | Kioti Tractors
My backhoe does not have a thumb, though one is available. And a thumb would not be helpful with the size of your rocks...which appear to range over 1000+ pounds.
I use my backhoe for utility line (water or electric) trenching, digging out rocks exposed at surface and mainly for culvert installation. I only have two buckets: a 12" and 36" bucket, and these do most of what I need for excavating. I don't do any digging out stumps with my backhoe, though many owners do use their backhoes for that purpose. I prefer to use a stump grinder for that job....grinding stumps 6" below ground. Saves significant wear and tear on my backhoe, because I grind over 60 stumps per year.
A backhoe takes a good week of experience, getting used to the hydraulic controls, before developing smooth operating procedures. You will develop the skill.
Regarding the Woodmax backhoes, those are not subframe mounted equipment. All are 3pt backhoes and are dangerous for your aggressive backhoe work. The pins on Woodmax are replaceable, but Woods uses greased swing joints like on a loader.
Which brings up the question, the John Deere OEM backhoe for your tractor is the 270B. And I believe it uses a three point hitch mount. If so, its incredible dangerous for your type of work. If you would be just digging in only soft soil or diggng out small rocks, it would be fine. But 1000+ pound rocks is a big job for the 270B.