Given you mention camping…
We have a roof box which is almost exclusively used for camping trips.
I tend to use it solely to transport our gigantic polycotton tent and its many accoutrements. The tent pretty much eats the roof bar weight limit on its own, and while it’s a massive pain to get it in the roof box, it’s marginally less of a pain than trying to fit it in the boot.
Plus if it gets wet, it can be wet in the roof box on the way home rather than being wet in the car.
Plus plus when you have to stop mid journey to dig out fresh trousers for someone, or a spare blanket or whatever, it’s in the car and hence easy to locate compared with finding it in a box above your head you can’t see into.
I bloody love camping, me 😂