Well, to "toggle off" just do a step to the side =P

But i agree should be a way to turn it on...it could be linked to light swing, just like light strike does to pugilist. This way you could activate and deactivate at will.

Enhancing enduring march would also be a good way to dealing with it. Think about an enduring march similar to defender...you toggle on/off, 30 minutes duration, 30 seconds recast and, while active, you will always having steadfast active. If steadfast happens to not be active, the enduring march effect will be forcing the activation of it.