I think the new SL100 racks are 29kg. Overall I calculated my total load including the rack at 93-105kg fully loaded. Too far over the Tesla's bar limit of 72kg, but comfortably under the 160kg of the stealth or Carasel. My Yakima Hold-Up 2 is 22kg, so loaded it ends up at 67kg so not a lot of margin and only 2 bikes.Can't imagine putting a vert rack on a model 3 - but my single-trail.com.au bike rack has an adjustment on the bottom to stop the wobble (put tongue in, tighten adjustment with spanner).
you would want a towbar rated for plenty of down weight capacity - the racks themselves are heavy - even before you get 4 bikes on it.
Aside from not wanting to run it on the M3, are you happy with the single-trail rack with whatever you're currently using it on?