Looks great ron, I especially like the insert retainer pin idea, that has to be a first, or at least I have never seen it before.
Where I park my tractor I have very little extra room, so I would need the receiver set way in close or even flush, never thought of that way to pin it so I don't have a hitch. Mines already filled with concrete so to late for me now, unless I really wanted to get into a tricky project.
I thought about welding one on the top flat spot but that is a little high for practical trailer coupling. Would still be good for other acs. though
My space constraint is such that I have to drop the box from the QH, then back up close as possible to the box with the 3 pt raised, just so I can close the overhead door.
JB