OK I'll try to answer with what I remember (at work).
Tire size is LT245/75-16 (or close to that)
Camper weighs about 4800lbs dry, and theres not much in there beyond that.
I'm usually content rolling 55-60mph when hitched up. The big grades slow me down to 40-45mph
According to build sheet, the truck came with the tow package, trans cooler etc...
Recently replaced water pump with new high-flow, running full synthetic oil, and dropped in a 180 degree fail-safe thermostat.