I like very much the third : the touchwheel. That would also be perfect for Powermate, if there were key Shortcuts assignable for touchwheel rotation
You may work on a simple OSK, also, for those who don't like the touchwheel, or do not have Touchscreen. this OSK would be half the screen height, with a button to move it from the down half to top half, (and maybe center half).
And you would choose in RRconfig for OSK type (touchwheel/Classic).
...just suggestions, you're the boss