Talking Past Each Other a Bit
I don't think there's evidence that Alaskan needs to build a better subframe.
I do wonder, however, if their standard design doesn't benefit from having only the center touch the bed. That's the most neutral area, and there's no weight directly over the rear wheels.
In a full flatbed build contact with the bed is triple. It must flex more.
Truck campers, like the Alaskan, have no subframe; they use the truck bed to hold the camper and distribute the weight. Thus your "stack" is Camper-pickup bed-chassis. Carl removed the pickup bed and replaced it with a flat bed, but the stack is the same. But the issue remains; you still need something between the chassis and the camper; you can't bolt a conventional truck camper directly to the chassis.
This "something" has a couple of goals:
-- Protect the camper from an unacceptably high degree of twist. Obviously, the "stronger" your camper, the less protection needed. Hence my musing that you could design a camper with an integrated base frame that was ready to mount directly to the chassis.
-- Reinforce the chassis or or at least distribute the weight so as not to act as a stress concentrator. As noted in many posts, some pivot designs, while protecting the camper from twist, have had the unfortunate side effect of concentrating all of the weight on only three or four mounting points and thus breaking the frame.
In the process, of course, you seek to add as little extra cost, weight, complexity, or height.
I asked the question as it appeared that the flat bed that Carl is using has been stiff enough on a one ton pickup to accomplish the mission. I would expect that it would work even better on a larger truck. I was thus interested that Carl would propose using a pivot frame on a larger truck when I would guessed that it would have been even less necessary than on the one ton truck. Especially if he goes to a simpler, rectangular camper without the suspended weight of the cabover.
Offered for consideration. Fortunately I still have my day job and don't have to bet my paycheck on this!
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