I have a B7100 with the B670 backhoe that was designed for the B7100.
My tractor is smaller than the 185, and the hoe is pretty teeny, and very anemic compared to modern hoes. Having said all that, the hoe has its own sub frame, which is attached to the subframe for the B219 FEL, which attaches to the front and rear of the tractor, tying it all into one pretty solid unit. I think anything less than all this rigidity is just asking for something to break.
JMHO.