Diki:
I ended up with very much a ‘two right hands’ approach, which is enormously fun to do and rewarding to pull off musically."

I sure haven't accomplished near the technical methods you have, but I always use the "two right hands" approach. I started out very simply by putting an appropriate sound to my left hand. Next, I sort of kept time in a after beat. I graduated to adding fill chords in the same key. It ain't rocket science, but it sure adds a great deal to my total sound.