Heavy Haul - Fuel Economy and Engine Life

[KWT880]

With the truck being so new and still under warranty I don't want to risk paying for a motor. Is there anything I can do tuning wise to improve the HP but change back to stock if need be? I don't have Insite yet but it on my list of wanted items. As for sensors I've read IMAP and Delta P. The truck has been on a chassis dyno and gets peak HP at 1500 RPM

1400 RPM - 440 HP
1500 RPM - 476 HP
1600 RPM - 455 HP
1700 RPM - 443 HP
1800 RPM - 401 HP

Gearing wise, when under heavy load (loaded and pulling hills empty) I should try and keep it around 1600RPM? When empty and light engine loads try to stay around 1400? What would you say is a heavy engine load? Over 15lbs of boost?