Re: ^...
Road service happened a couple days ago. Went well. He was there to tighten a very loose and about-to-fall off right rear side tail light. He ripped off 5 or 6 interior panels out from the back of my Y with his hands (no pry tools!) and tightened (read - bent back) one plastic clip that apparently holds the tail light on. No metal screws are used to attach them! That operation and the reassembly took about two minutes. His fast skill at this tells me that this QC fix must happen often enough.
Now, about the flaps. He replaced my flap that had fallen off, and used two new expander clips. I was able to keep the old flap, but sans the old clips, sadly, because I wanted to have some of those in reserve for the next time one goes missing. Next, I asked if there is a Tesla part number for the expander clips. No. The one and only part number is for the entire set, which includes clips. They are not available separately. Also, these clips are not used anywhere else in the Tesla world, according to the service tech.
So if anyone can find where to buy these things, and can confirm they are 100% identical to the OEM Tesla mud flap clips, please post where they can be purchaesed from.