The backhoe recommended is done so based on manufacturer specs, factory/OEM made mounting hardware and matching the weight and hydraulic capacities. It's an OEM solution.
That said, How handy are you?
If you are handy and have access to the means to do it you can mate almost anything to something else. You would have to fabricate all the brackets to properly handle the load/force of a backhoe against the tractor itself as well as coming up with a solution/plumbing for the hydraulics. You would likely also have to troubleshoot all the mechanical failures on your own or utilize specialty shops for various issues VS dealership