The real problem with running a manual behind an auto is that if you miss a shift on the manual, you"ll have to kill the engine to get it back in gear. And to use the hydraulics without moving you"d have to shift it to neutral and put the auto back in gear. And what happens when you go to reverse with the auto? Your hydraulic pump turns backwards.
I"m sure you could fab up a mount for an engine-driven hydraulic pump to go where the A/C compressor is or something.
A 3 pt isn"t going to work real well if the rear is suspended. Jeep found that out when they tried selling plows after WW2.