here's and idea:
factory rails with slots + thule or yakima cross bars mounted as needed to mount Pelican 1650 or Stormcase similar via drill-through for U-bolt attachment.
Tough, won't "break loose", waterproof, doubles as standing platform.
Here's something cool too, my 48" fiberglass waffle boards mount directly to the factory slots via DIY aluminum slot-tab, tapped for threaded rod, wing nut from above on hold-down plate. These double as standing platform if the rack isn't mounted (my Hannibal mounts such that these still tuck underneath).
There are ways you can put the things normally ON a rack directly onto cross bars on the factory rails. This eliminates the rack weight, cost, wind drag, height.
I HATE the cargo bags. Everyone I've known with them complains of water intrusion.
I wouldn't hesitate to run all sorts of routes with any of my Thule boxes but their clamps are full pincer-claw, like a logging machine. Worse case, could use a plate inside to distribute stress plus U bolts through the same slots in the box bottom used by their pincer-clamps. I have had 2 Thule up there before totaling 33 cubic ft.
-
I basically only mount the Hannibal rack for purpose of using the attachable Hannibal awnings to make "rooms" primarily over the rear but also the full 90" side.