My 2017 S has what I call "Cr@p pockets" in front of the rear wheels (looking downwards on the forward edge of the rear wheel):
These definitely fill with ice and snow in winter, and you can see some summer detritus there now. There are a pair of holes on the inside vertical edge of this pocket, but no mounting holes on the outside body panel. So a cover needs to only mount on the left edge. I've been wondering how to cover them up, at least enough to reduce the amount of snow which lives there.
I've been thinking that I need something like perforated angle-iron (but made of plastic) to connect to the frame with cable ties, about 6 inches tall; plus two layers of coroplast. The coroplast would extend down over the bottom lip of the Cr@p Pocket, and above that, would tuck inside the outer body panel.
If there's a Nissan part for this, that could work too.
BTW, I get the biggest snow chunks in the LEAF wheel wells of any car I've owned. Even the front wheel wells, which don't have Cr@p Pockets, will build-up enough snow/ice that when you turn the steering wheel, you can hear the wheel grinding on the ice chunks.