Aside: humvee is still using `navscene`, which will probably cause headaches.  Making the change will require that the humvee's inner camera extend `navigable.vwf`.
But more to your point, I guess the model really needs to have a concept of a shared `navObject`, rather than just a shared camera.  The view can query for `usersShareView`, and if it's true, query for that shared `navObject` and set that instead of going through the process finding a navObject on its own.