Dually's dont turn worth cr*p and he's probably right that the 630 singled will. There's one big difference he forgot to mention....weight.
So before you go blowing a bunch of cash you need to check your local RV licensing limits....here in Ontario Canada its 11000kg's truck trailer combined all in (so truck, trailer plus everything inside) if you go over that you need to up your license from "G" to "B". Also because the truck has air brakes you will need an AirBrake endorsement added to your license (ontario = 2 day course and 400$ per person driving). Now in Ontario they also consider a "truck" for pulling a none commercial trailer an entity with a "box" so the 630 or any truck really doesnt qualify which is why you see those Freightliner M2s with the boxes at horse shows). Also if you are beyong "X" feet long and over 11000kg you might have to move up to an class "A restricted" license.
So long story short....do your research before you plunk down a penny or you might be in for way more than you bargain for....the US has different laws for different states as well. Sadly its not all as easy as Youtube makes it look.
Not going to get into any comments about RV places refusing HDT setups as well as i only hear of such problems ....