Yep I've been ground driving her for over a month now, she picked it up really fast, well we were toodling down the road start stop and trotting in under ten minutes. She's very good with vocal cues since we had been working on showmanship halter.
As of right now Nova can:
-Flex both left and right and it very soft with or without the bit.
-She tacks up very quietly, I never tie her and she just follows me usually.
-For ground driving without shafts she is able to turn right and left (she does turn her body right now, I'm gonna try the pvc pipe you suggested sounds good :) ) She walks trots and stops on verbal cue.
-I knows how to start and stop verbally lunging (I don't go all out lunging her. I just barely started her walking out away from me on the line andI only have her go around a couple times in both directions.
-While just leading she walks, trots, lops, stops, and backs depending on where I am standing and pace.