Bedlam wrote:
The truck will handle the fifth wheel just fine. The engine choice is what is holding back the ratings - It will require more distance to get up to speed and hills will be slower. If your truck does not have the camper package with rear upper overload springs, you may need some suspension aids to handle sag.
Without knowing the type of motorcycle you plan to carry, it's hard to tell how much it will affect your pin weight by hanging it off the rear of the fifth wheel.
I agree with Bedlam, the 250 will do the job. The 5.4 will be a little weak on uphills, and head winds. It is 300+ HP, and 365 FPs of torque, so if OP is not in a big hurry, this truck will work.
The OP has a motorcycle that weighs on the short side of 500#s. I would suggest a wheeled tote, that fastens solid to the FW at two points. I am not a fan of hanging that much wt on the back unsupported.
Jerry