I made a hoist into the roof of the garage. With a rope that goes around it.
We've had a montblanc box (320l) for years. However I couldn't find the closed rail feet to replace the old ford focus bolt into roof feet. So in the end I replaced the old whistle at 50+ square roof bars with some Thule aerobars and closed rail feet. Still has wind noise but that's a given considering the size of the box. The montblanc grey has faded to a green colour (it's been in the garage and out of sunlight for most of it's life).
The main thing with roof boxes is the difference between mounting location of the foot/bar and the separation supported by the roof box itself. On the focus, I had to drill an additional set of holes in the box to extend the range of the box spacing by a bout an inch. The Peugeot 3008 SUV has more forgiving spacings for the feet, however the roof curve of the ralls means you still need to keep the front of the box forward.