I'm surprised that it fit the 99 but not the 07. When Ford went to the Super Duty in 99 they made the cab taller but I didn't realize that they made it taller since that time. Well learn something new every day.
To answer your question I would see no problem with what you are looking at just keep a lookout on the bottom of the camper tub and make sure that the foam doesn't collapse and let more of the weight set on the 2X6. I used the pink foam in my 2002 Chevy to get over my 5th wheel plates with a Northern Lite. Just make sure you get you bed mat to fit on top of all of it or it could very easily slide aroiund some.
ON EDIT: Looks like Gripnriprod beat me to it. I'm a slow typer and make a lot of mistakes.