Hi,
This is a minor comment. Using X-Camera plug-in to view the passenger compartment shows some weird textures on port side + missing & overlapping windows on both sides. I guess that's why the view isn't available via the normal camera keys at present.
They didn't unlock it because it's not fully finished. There is just a low res version in there. What you can do to walk through it and set views is open the window, go as far as you can out the window, close the window, and now you're free to go around .