FJ Cruisers of Northern California
Baja Rack makes a drop in: http://www.bajarack.com/toyota-fj-tyfjoemrck-rack
Or just strap them down with bungie cords and ratchets and hope for the best!
I built my own. Completely portable, 12gal, cost less than $200
I have the Roto Pax system. but i also have a baja rack... but i think there are spots where you can mount it to your stock one as well. http://rotopax.com/
It's pretty easy to mount rotopax on the stock roof and crossbars racking using the rotopax universal mounts.
I have a couple of these:
They are low profile and strap down easily.
Has anyone considered moving the spare tire to the roof (I have a Baja rack) and putting fuel cans on the rear?
I don't know about you, but I would have a hard time getting my spare tire up and down from there... not to mention the huge center of gravity shift that would cause.