Sorry, I can't be of help with this because I have a tow bar installed after many years with roof bars in other cars,
I did hate my previous roof bars! It was so hard to put anything on top and my previous car was not as tall and the NX.
I would recommend a tow bar with some system for bikes or suitcases. I'm extremely happy with the system I have.
Check my previous posts.
Cheers!