After catching the front on the ground quite a few times, I decided to grab a set of cheapo scrape guards and stick them on to see how long they lasted (and if they even helped).
My main point of impact is actually on the factory blocks you can see here on the left and right:
The kits generally come with like 8 or 10 or so of the strips. They are 3M adhesive and they can be cut to size/shape as required. I left 2 of mine as spares, with the expectation they would fall off - but 6 months later mine are still there fine now so that was unnecessary it seems.
My Amazon kit was £10 - this one:
Fitting was like 30 minutes - i cleaned the whole area and then stuck them on where it felt like it would be the lowest parts of the main tray, and, the leading edges of the most extended parts of the actual splitter.
Interestingly it seems my main points of impact are my undertray further back, and not the actual splitter itself. But hopefully by landing on the extra bit of height now, I'll save some wear and tear further back.
NOTE:
One thing that is worth noting, in my experience at least, there have been two occasions in the 5 years I've owned the car now when I've started suddenly getting a lot more grounding at the front. Each time, on the next service it has had, McLaren have identified a broken front coil spring and replaced it. So despite the drop in ride-hight not visually being noticeable (well, by me at least!) - I suspect the extra few mm of drop on the nose make it that little bit more susceptible to grounding out.
So - If you suddenly start hitting the floor a lot, check the springs, I've broken 3 in 5 years (2 front, 1 rear) and it's quite a common thing on these.
Scrape Guard
There are some far more significant versions out there also which might be worth considering if you need heavy duty protection (and arguably something that will stand up to more abuse on the track!). This is an example, which apparently bolts/screws directly into the splitter to provide full coverage:
