I have a 2011 Ncv3. There were a series of plastic plugs in the roof rail mount holes that were painted over at the factory. Upon investigation, I found that nothing was threaded. In order to secure my Unistrut rails, I installed plus nuts in the holes using the three forward holes for the front section and the three rear holes for the back section. There are two sections for few reasons. One is that the fantastic fan is mounted mid roof. Another is that the roof rail slots are curved, so a 10' length of Unistrut is not going to sit in the slot. The solar panels are mounted to front rails with a slight cantilever, forward of the fan.
To seal everything, I used urethane body adhesive between the unistrut and the body, then applied dicor sealant to every washer and bolt assembly. So far so good. I plan on putting a air deflector on the front of the solar panel mount because in high head winds, the uplift causes the unistrut to creak.