You know there’re no rocks in Michigan! Seriously, the “standing part” of that plow is pretty long – six feet or so – and is actually a “T” profile (stand on top of the T) so the bottom of the T acts as a kind of rudder. The Moldboard is maybe 4 ft long with a hold bar on top to help balance you and control (not steer) the plow by lifting or leaning on it. I wish they had a diagram of how to build one – I’d do it.
Geoff, somebody forgot to tell my fields that they have no rocks:) I didn’t think of that but if the “rudder” is longer than the cutting edge it should give pretty good control.