Important flat bed Information
This is specifically about putting an 8′ flat bed on a 6.5′ bed truck:
There is absolutely no way to ensure the truck chassis is or can be loaded correctly in that application. Any FMVSS/CMVSS/NHTSA approved Upfitter would have to perform a weight and balance study to make sure the chassis is loaded properly. When the center of gravity approaches or moves behind the rear axle it will unload the front axle which is incorrect and puts the center of the frame in a tension situation rather than the compression situation that they are engineered for, hence the weight and balance study to confirm.
Ignoring proper weight and balance will lead to damage when exposed to a healthy amount of inertia and your steering and braking will be negatively affected.