Kevin,
I just ordered both the swingout extensions and the bracket extensions so I can carry a Laredo SC on my F350 DRW truck. I am in the same predicament. Your F450 is NOT wider than my F350. My F350 is also 96″ from dually fender to dually fender. The tires on that F450 are definitely not stock. Those are much wider than stock.
I am curious about the way you stacked them, though. I have Atwood swingout brackets on my 1998 Lance 990 and the swingout bracket mounts to the camper and then the extension mounts to that. This is so that the entire assembly swivels in out of the way of the truck mirrors and is tight up against the camper. Is there a reason you stacked them the way you did?
BTW, in my photo I added an additional extension to the jack bracket because my 1998 Lance 990 is only 93″ wide. The regular swingout brackets would clear my fenders but it was extremely tight. I just wanted a little more wiggle room.
