Your best bet for
large oil change access without removing the entire undershroud, believe it or not, is the OEM undershroud. Once you train the flap to hang back out of the way of the draining oil, it definitely has the most clearance.
Also, Z1 doesn't make a separate undershroud
AFAIK. They just sell the ZSpeed one. The other brand I've heard of is Toll Booth Willey.
My recommendation is just get the ZSpeed one and plan to remove it entirely when you do an oil change. You pretty much have to do this anyway if you want to only lift the front of the car and leave the rear wheels on the ground when you do your oil change.