Weird that your truck is 400# lighter than my XL. Sounds like a flooded scale.
The 7.3 is nice, but you don't need it at all, for a 10,000# truck camper combo. My work truck, 6.2l, weighs 11,000# with it's loaded utility box and crane, and even with pitiful 3.73 gears, it can run over or...