Put a hitch on both of my model 3’s, and the egolf before that. EV’s tow great, but you only want a bike rack, so leave off the wiring and chain mounts (stealth hitch).
It doesn’t “void the warranty” in the US - the manufacturer would have to prove the item caused a failure of some sort - for example the hitch (made of steel) mounts to aluminum. Improperly installing the hitch without the plastic isolators will cause the aluminum to corrode. This would definitely void a warranty corrosion issue.
Dimensions include a curved side. Width is 17 11/16
Height max 6 3/16 min 5 5/8
No mm tools handy. The minimum height has a radius and may be off.