I have one of the agrisupply units, which looks identical but was cheaper when I bought. Mine installed using (2) 9/16 or 5/8 bolts, nuts & washers. I initially installed it on the tractors PTO stub to use on multiple implements--that was a mistake. I avoided damaging anything except the PTO shaft I cut to make it fit, and changed the mounting position the first time those whirring spring/bolt combinations slapped the control rope, and got me thinking what better odds for snagging... me... branches to wind around the shaft and slap at the hydraulic lines or wiring... or me! You run a winch with you off a tractor, and the pto stub is right there. I didn't even need a slip clutch for the winch, as the control rope tension is the slip clutch, but I wanted to have the clutch on the tractor stub to use for everything... like you mentioned.
It's too dangerous a spot to mount it, its too heavy to mount there, and is unnecessary on many implements. Hard on bearings.
Regarding shielding--that's a personal choice, but it is the ounce of prevention on a driveline that makes a trip, stumble, loose article of clothing a heart-racing instead of heart breaking experience. Nothing beats a cautious operator, except mechanical controls that keep all operators (regardless of experience) away from the danger. They are the system set up to isolate the rotating shaft from everything else.