I often day-dream of putting a flat-bed on my Dodge, but I'd lean towards a more permanent mounting with nice alum. storage boxes up and down each side in the gap between the camper and the flatbed. The one problem I can't get around (actually the first problem is $$$) is the height of the floor seems to go up about 6" with a flat bed. Do you find this negatively impacts the COG? Sort of, but not exactly, like this...
Also just out of curiousity, what is the weight difference going to a flat bed? I would guess you can pick up a bit towards the payload.
-Vic
If you consider the flat bed can be moved to different trucks, and the old bed stays nice and pristine till it goes back on. Price in the long run is not bad.