Like Tim and Colin I prefer to use the tonneau and the storm cover. (and like JohnV6 I value it covering the louvres)
This does keep prying eyes away from the interior, which is not the case with the hood up.
One refinement I introduced on one of our Scottish jaunts a few years back was the addition of a length of 4mm shock cord, running windscreen spindle to rear rack over the centre of the windscreen. It doesn't need to be tight, just enough to make a slight ridge for the storm cover. That way rain sheds off it rather than pooling in the middle, which it can do if you have just the tonneau cover on.
This pic is a pretty good advert for the John Taylor cover, everyone's got one. Mine's the green one.
![[Linked Image]](https://www.tm-img.com/images/2018/09/03/TJH_2378.jpg)