To go back to PM's original post: You can tow a substantial 5th wheel with a 2500. In fact you can more safely tow a bigger 5th wheel than most foks could tow with a 3500 a few years ago. Unless you have VERY grand plans, your truck will not limit your decision about a trailer -particularly for, as you mention, you and your wife (not you and your wife and your buddy's jeep rock crawler).
My 2014 leaves my 2004 in the dust, and i loved that truck, and had all kinds of neat upgrades on it. I think the odds that you will need a Kelderman system (not that it isn't neat) are virtually 0. You can solve the truck leveling problem with a relatively inexpensive airbag system (Ride Rite; Pac Brake), and that really IS a nice feature - your truck rides better, steers better and aims its headlights better with the trailer. It doesn't increase your GVWR, but that's unlikely to be your limiting factor.
ENJOY your super-cool new truck. It's capable as hell!