I agree with your concern. The Model 3 is very low from the ground.
I installed a Stealth Hitches with a 2" square receiver for my bike rack.
See my experience:
The first time I used it, I heared this big "Bong" noise when passing above a dip.
You can notice that the bottom of the receiver was 7 inches above the ground.
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I contacted Stealth Hitches and they recommended to use a 6 inches raiser.
In fact this was even worse because this extended the receiver by few inches
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After getting this second "Bong" noise I decided to test if using a ball mount tow hitch would saved the problem.
So I welded a square 2"x 2" and 6" long receiver on to of the ball mount.
This gave an extra one inch of clerance, and the bottom of the receiver was now 8 inches above the ground.
View attachment 924279
In fact, this was not sufficient enough, as I heared for the third time a big "Bong" noise
However, I noticed that the ball mount could be moved 2" 1/2 closer to the rear bumper.
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So I decide to shorter the ball tow hitch.
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And welded everything together
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So far, I don't have the big "Bong" noise that I experienced when driving above a dip.
View attachment 924287
Note: I would not recommend using this custom hitch receiver to tow a trailer but this seems fine for a bike receiver.