Good question, and idk. I like your approach as to how to address though.Is the locking pin going to be a problem? Watching the video it appears you would need 2 hands. One to pull the lock and one to twist the shaft.
I have been getting a popup ad for the same idea of a coupler. On this ad the locking pin is not built on. Maybe you could unlock it and then remove the shaft. Thus more of a one handed operation.
Second idea was a something like a clothes pin that after you pull out the lock and slide the clothes pin onto the shaft of the lock to keep it unlocked as you attached/unattached the PTO shaft.
Keep on keepin' on.
I have an idea that Im going to try in the next few days before I order anything.
I will be posting it if it works