Been awhile since this has come up so here is my standard info for those currently discussing it.
I had this on both my 06 and now my 08.
My door is still attached and hinges are tight and closure is snug as always.
Oh, and I use it while offroad, often. So I don't think two cans is gonna be a problem if you brace it right.
Even with careful fuel calculations I have put in the extra fuel, several times for piece of mind when headed to the first chance to fill up near the end of a long trip in the middle of nowhere, in the dark, and in the rain.
Another thing to consider depending on you type of wheeling would be departure overhang. On this obstacle I bent the license plate coming down, so anything hanging out past that could be a problem in extreme cases.
As always, my concern would be having the cans down low in a rear end collision but then I have not tested mine for that either!
Here is one I saw many years ago that may give you some ideas.