We have an Atera and mudflaps - seems almost always to be the mudflaps that scrape rather than the rack except for very sudden changes in angle or scrambling up a rocky slope (inspired by another post on here tried to follow satnav to a high mountain lake to go paddle boarding but it turned into a rock-strewn path and the rack grounded out too).
Ferries haven’t been a problem. On the Atera there does seem to be a small amount of vertical float and will try to remember to pull the rack up as I tighten the clamp (but this will make the clearance on the vertical rack bar even more snug....)