I just discovered an easier way to capture lightning - use the time lapse function of the 7D II to continually do 30-second exposures.
First, I set the aperture (normally wide open, the 16-35's IQ is excellent even at f/4) and ISO to properly expose the scene with a 30 second exposure, before the lightning bolt strikes.
Next, I point the camera to the general direction of the sky where lighting
strikes are active, fine tune the framing for composition, and manually pre-focus on a foreground object in the distance that I wish to be sharp. The deep DOF of the UWA lens should also render the lightning bolt in reasonably good focus.
At this point, I enable the 7D II's time lapse function, then press the shutter button. The 7D II will shoot long exposures non-stop until I turn it off when the lightning activity subsides. I usually set the interval between shots to 2 seconds to give me time to turn off the camera in between frames.
Here's a practice shot using this approach. I'm hoping the lightning display will be over a more photogenic location in the coming nights. Casting a wide net (long 30 second exposures), and doing this continually, should greatly increase the chances of catching a lightning formation at its sweet moment.