Dave,
My best guess would be that getting the camera to work on my new Kenwood was as easy as plug n play (maybe with an adapter?) and that the steering wheel controls were part of the work on the MB canbus.
I remember being very pleased that the buttons on the wheel worked again. Sorry that I don't remember more. Mother Benz is very persnickity about any non-Benz items added to the chassis...
If I recall correctly, Mercedes changed several chassis things in the 2018 model year.
Again, ours is a 2016 View on a late 2015 chassis.
Regards, Mike