On your list of trims, why no Outdoorsman? It's basically just an SLT with some tow hooks and body colored trim.
You'll likely be over 2500 GVWR of 10,000# with any loaded 5th wheel you are talking about. For comparison my 11,000# loaded 5th puts me right at my 10,000# GVWR but I have 3000# payload with my Hemi. A diesel puts you more around 2300#. I'm usually the first to argue that a 2500 is the same truck as a 3500 and that axle weights are what really matter. However, when starting from scratch, you might just want to stick with 3500. If for no other reason, you'll keep the blood pressure of the weight police on the forum down. Basically, I just want to be sure you are aware you will be over payload. As long as you are okay over payload and under axle weights you won't hear me yell at you.
I like my manual air bags as opposed to the auto leveling Ram offers. A buddy has that on his truck and it tries to out think him sometimes. Granted, I get cranky about things being too automatic so it may not be that bad. My bags couldn't be easier. Fill them, empty them, as easy as that.
