I have personally gone way over the hitch rating carrying four electric bikes on 3 separate Model S's equipped with aftermarket 2 inch receivers, no issues whatsoever. (I did pull the batteries to reduce some weight, but I was about 200 lbs over with the 4 up bike rack included. One of my Model S's at 120K had an air shock leaking, maybe we can blame that on my numerous "overloads", but I don't think so as he other side is still original, but I suspect that might have happened when I towed my neighbors 7500 lb boat up his long driveway to prove a point or when I towed a trailer with one cord of very green Split Red Oak @ 5000 lbs (sans the trailer weight).
I also carried a Zero 5.7 FX Motorcycle, same deal, I pulled the batteries, dropping 100 lbs, but I was still over when you included the rack, by about 80 lbs. Again, no issues, did 80 MPH on the highway, just had to charge more often, which was a perpendicular charge stance back I those days..
I haven't used the Model X yet for this same setup, but the hitch isn't as good as a static fixed hitch, with is why the rating is so low, I may end up pulling the Tesla Hitch and going aftermarket for more strength, but then again I don't need 4 bikes anymore as both kids have their own Model Y's now (both with aftermarket hitches) - I have now installed 5 hitches on Tesla's and seems to get easier each time... hell we even put one on our Miata... so that is six hitches, no seven, I did the FJ too.
Put the heaviest load as close as you can to the receiver when carrying hitch mounted carriers. Towing is different, balance the load with the weight biased toward the hitch at full load. You know you have too much weight forward if the ride is rough or the front end feels light.