That's a 7 foot model.
It is really too big for a B7100!
Straight comparisons:
The specs
B7100; 13 PTO HP
BH; 15 - 35
B7100; 3.6 gallons, 3 gpm at 1570 PSI to 1710 PSI
BH; 4 to 5 GPM at 2250 PSI
B7100; The three point lift is 400 lbs, so that gives you some kind of comparison as to what kind of weight you should hang off the back.
BH; 645+ lbs
Bush Hog Model 665H, Cat 1 & 2, 3-Point Mounted Backhoe.
* Specifically designed for smaller Compact Tractrors with 15 to 35 PTO HP.
* 7'- 0" Maximum Digging Depth.
* 6'- 6" Digging Depth with 2' Flat Bottom.
* 180 Degree Horizontal Swing Arc & Bucket rotation.
* 5'-0" Loading Height w/Bucket at 60degrees.
* 8'- 6" Reach from Center Line of Swing Pivot.
* 2450lb's of Bucket Cylinder Digging Force.
* 1250lb's of Dipstick Cylinder Digging Force!
* Hydraulic Req's are 4 to 5GPM & 2250PSI.
* Weight less Bucket is 654lb's.
How are you going to power it?
The on board Hydraulic system of the B7100 is not up to the task, no where close
And the PTO output would be very anemic trying to run a pump to supply 4 to5 GPM at 2250PSI
You'll also have to add a tank and a pressure relief valve.
Yes I know I'm being negative to this endeavor and a captain Buzz Kill
but it's real world specs, there not much room for spinning it to make it work.
Buy a bigger tractor, like an L, to run it on.