Wow! - congrats on your new truck....that's pretty much the exact model/specs I'd also get if a new truck were in the cards for us...
Our Exc with the 137 inch WB handles our 28 ft AS like a dream, so you're new rig should have no problems at all...good choice...
We recently sold our 99 F-350 4x4 supercab (long bed for a Lance camper) and really liked that cab configuration - except the short bed is a much better choice for towing...
That 4.10 gearing should work great for for the best all-around towing, etc...wish I had those gears in our Exc (we have the 3.73s), as I think it would be better up in the high mountains...
I'd also like a LS diff in the rear - but I must admit I didn't have any trouble running on the loose sand dunes with the Exc last fall when I put on my big rims/tires (18 inch/325R65/18-ProComp Xterrains) from the F-350 - so the LS diff wasn't really needed...
Have lots of fun with the new rig...
Ray