To the best of my knowledge, those cross beams are just attached to the floor, not into structural framing. I could be wrong on that. I think it is there just to keep the floor off the truck bed.
Florida,
That is one good looking camper. You have a great camper setup. I love the flat bed Alaskan's that Brian does. My father has a 10 ft flatbed and it's a wonderful setup. Enjoy!
Ten feet would have been luxurious, but I didn't want to give up the cabinet and spare tire set-up that I had already paid for. Having the crew cab gives me tons of secure space but lengthens the truck - it comes to nearly 24 feet! If I could live in a shorter vehicle I would just for off-road capability. This is my second home. I need the space.