Had a Thule roof POD -- for many trips, Roper Bar, Rosella Springs, Gibb River Road -- many rough roads, did reinforce and change the mounting system, with some square aluminium tubing..
POD are excellent, no dust inside, unlike people who used standard roof racks with baskets, which they had to tie everything down, with a POD it's just a matter of closing the lid, although we really did fill our's up a bit, which did result in a challenge to close the lid sometimes.