"Um you better look at those specs sheets again :S"
Here's a thought.....
MAYBE the OP has taken HIS truck to the scales with it loaded up and after getting the numbers, performed some simple mathmatics in regard to his RAWR/GVWR and now knows HIS ACTUAL payload for HIS truck, hence the 2560lb number. Hmmmm.....mind-bowing, right? To that end, any "brochure/pdf" analysis is simply not applicable to his situation. :)
The OP seems like a pretty proficient fella', and even mentions that if the XD isn't a perfect fit for the job he will adjust accordingly.
Now, just for kicks ;) I'm going to make a comment on his actual question regarding short bed trucks and hitches.
I had a Ram short box and used an Andersen rail mount and an '18 Reflection. I had lots of clearance on every front, although I did watch carefully when backing up if there were any dips etc in the approach to the site, which I would have done with whatever hitch I was using regardless. Never had any issues.
The hitch has a few adjustments that you can make, so that's a plus as well.
I looked at the XD's gooseneck set up on the Nissan site when I was searching for payload PDF's.....(lol., no, I wasn't) and it "appears" that the chain attachment points in the bed are pretty close to the gooseneck ball? You might want to take some measurements in that regard to see if the Andersen footprint will fit in-between everything. Could be my aging eyes, but would be worth confirming.
Do come back and let us know how everything turns out, and Happy Camping :)