I don't think you can order a 2016 RAM HD any longer, I believe orders closed last week.
If you are looking at a 41 foot fiver, that will likely put the pin weight of the RV around 3,000 pounds which exceeds the payload of a 2500 truck. You are in 3500 territory and may want to think dually.
I have a Montana 41 footer (3790RD) which comes in at 13K pounds dry with a pin weight right around 3,000 pounds equipped. I have a RAM 3500 SRW Cummins to pull it around. I have RAM's rear air leveling suspension and yes, get it, works beautifully.