No great choices.

One of my cars had a built in tow hook just under the bumper and welded to the frame. I used to loop a cable lock thru that.

It's really just a nuisance lock to prevent somebody from casually stealing the bike. Anybody serious who wants the bike is going to get it.

That's pretty much the case with any mounting system - hitch and bike tray, roof system, etc... although I was once able to U-Lock AND cable lock a bike to my roof Thule. That plus the fork lock pretty much meant they would have had to spend some time defeating 2-1/2 locks.

Best solution is store the bike in the car.