Flatbeds vary a good deal in construction and size , so do TC' s . The best thing you can do is measure , measure and measure again . Most TC' s drop down after the eight foot Mark so they cannot be pushed forward if you get a longer flatbed . While this gives you extra storage space up front it will probably put more weight behind the rear axle . As mentioned , Ford's seem to have a higher cab than the other two so the camper may have to be raised some to fit over the cab . You want to limit this as much as possible because the flatbed is usually higher than a pickup bed , add to that a basement model TC and you are really getting up there . The headache rake will be dictated by the height from the floor of the camper to the underside of the cabover .
That being said here is what I have and done. I have a 60" CA with an 8-1/2 ' aluminum flatbed with 1/8" diamond plate with 3" I beam cross members . The camper has 3/4" x 1-1/2" wood runners under the floor every 12" running front to back . The diamond plate holds it like glue , no rubber mat . For tie downs I used 4 short ( front ) spring loaded Anchor Guard turnbukkles from Torklift , same as front Happijacks . On the bed they attach to 1/2" D rings bolted through the bed to a reinforcing bar that spans three cross members . Over a decade and nothing has bent twisted or broken . Good luck
