We had the same question. The 2017 f450 pickup has a slightly
larger diameter rear axle than the f350 pickup if you look in the specs. Ford went with
a new rear axle in their super duty for 2017 but their spec diameter
seems to increase with the model ranges from 350 on up to
the chassis cab 550. It would really be worth a look at the
chassis cab 450 and 550 if you are going to haul a truck camper
and a larger trailer. Those trailer tongue weights can put you
over your rear axle rating fast. Your actual cost in a chassis cab might be less even with putting a nice flatbed on it with boxes. You could get leather, nav and such if you
like. Just watch for that rear axle ratio. Maybe go for the 4.30,
but interestingly the GVWR and frame thickness gets downgraded
in some of the Ford chassis cabs when choosing something other than
4.88. This will affect licensing and your insurance.