I have a 3500 dually and tow a Landmark hooked to an ISR Pro Series 20K hitch. Pin wt. at 3,400 squats the truck to just below bed rails being parallel with bottom of the camper. I also use ~35-60psi in my Firestone airbags to level and that's based on weight I add in bed of truck and basement of 5er; still experimenting with air pressure to figure out what gives a better ride feel. I have plenty of clearance between the camper and bed rails; don't have a specific measure, but I know it's in excess of 9" and min bed rail clearance recommended is 6".
The Reese Titan 16K appears to have at least 4-height options, so the hitch is plenty flexible. I'd recommend leveling the trailer and measure distance from bottom of the pin to ground. Subtract height of hitch and another 2" since you'll need a picture frame assembly to attach the Reese hitch onto the new puck system used by Ram in the 2014+ build. The product of this math should get you close to the bottom of the bed rather than the bed rail height. If you're within ~7" you shouldn't have any problem with leveling the rig.
The next check would be to measure from the bottom edge where the pin box is attached. I would compare that measurement to the height of the bed rail directly over the axle. That will give you a true measure of clearance regardless of how level the trailer is since it's at the pivot point of the truck/trailer connection. This is the max clearance you'd have.
This is the same process I used when purchasing our Landmark and truck comb. Not a perfect answer, but it should get you in the ballpark to feel more comfortable on how it will all fit together.
