There are a few options for rear plates (they actually call them "mid" plates), but they cover the area under the rear motor and not the part from there to the rear bumper. The plastic cover from the mid plate to the bumper has no replacement that I'm aware of. If you are concerned about driving through deep water, just drill some drain holes on that plastic cover.
I just saw this thread due to the preceding new post today, otherwise it's been basically a discussion from 1H 2021.
The big news I think, is a recently new offering of front and rear aluminum skid plates in the aftermarket space. I have a set on order from RPM Tesla, placed while they were having a Holiday sale just before Christmas.
RPM is already listing sets for M3 and MY and they have promo/installation videos up on YouTube, but you can easily access them by viewing the product pages on the RPM website or mobile app. Go to
Menu->Collections->Model <3|Y>->Noise Reduction Kits
(read on for more re the Noise Reduction aspect).
I should note that I also see very similar products from TesBros, check out their YT channel. However as of a week ago, I don't think they were yet offering all the versions i.e. front and rear for 3 and Y. In my research, I did note a very similar-looking thing on Alibaba, and experience suggests that over time, other Tesla aftermarket suppliers will resell similar products from any Chinese source. Some people like to try going direct via Alibaba or AliExpress, but I see value in buying from and supporting the resellers, especially when they make the videos and provide the information so that you can do that research. I don't have much experience with RPM and I know they're not always the cheapest, but they seem to come up with new accessories earlier and/or more exclusively than some of the others.
RPM does charge a shipping premium for these products because of the oversized boxes, but those of you in Southern California could save that by picking up from them directly. I went in with a friend of mine and we ordered a Y set and a 3 set, that didn't really save the special premium but did save on a standard $100 shipping charge that also seems to apply. It doesn't look like the order has shipped yet, post-holiday.
I did note the existing Mountain Pass Performance skid-plate product and watched a video. That one is a little more plain, basically a big rectangle, but I have no reason to doubt it does the basic job. These newer ones are more custom-cut to closely resemble the heavy-fiber OEM factory covers. RPM's description notes that you can optionally leave the original covers in place and install these aluminum ones as an additional layer; I will probably make that decision the day I do the install. There is a slight weight consideration as the metal covers are already somewhat heavier than the originals. I'm hoping that the front edge of the installed cover will sit flush behind the lip of the bumper in such a way that splashed water won't be forced inside (we don't have a lot of rain here but when we do, deep running water and puddles form quickly). I'm thining the extra thickness with the original cover in place light not allow that flush installation to occur. We'll see.
Also egarding layers, a significant feature of the RPM product is that it includes a layer of urethane sound-deadening material already stuck to the top side. I imagine that without that, the new metal cover would have been noisier then OEM; with the urethane layer they claim it's quieter.
One thing that I don't totally understand: most of the photos show a little rectangular access door with its own set of screws. It looks like some kind of service access, but I don't know what it is and I don't really see it in the photo of the original cover- but I haven't been under the car yet myself. Also I don't see this separate piece in every RPM product photo, possibly some were taken on prototypes that didn't have this feature. TBD.
There are also some videos online discussing whether the OEM fiber cover is a problem, e.g. does it become weak and tear easily when wet? The answer seems to be no, not really.
Overall, I decided that it would be a good thing and a form of mechanical insurance to buy the aluminum covers aka skid plates. And watching the installation videos, I was impressed by how complex and delicate some of the motor components and wiring appear to be above these covers. Statistically, it's most likely that any given owner will be well-enough served by the OEM covers, but there is always that chance that you will hit a piece of debris that will penetrate the fiber cover and do some nasty damage. Damage that would have been avoided or significantly reduced with the more substantial shield in place.
I'll report back if I encounter any problems with the installation or any other disappointments.