Back when I was a shadetree mechanic and cars/trucks had spark plugs, points and no computers, I probably could have figured out your problem. Today, any time something goes wrong, you just blame the computer. In this case, you very well may be having a computer issue....it may be routing power to a component that is discharging the battery randomly. With any luck, your dealer or a good mechanic with a diagnostic computer may be able to pinpoint the gremlin in your truck.
2016 Chevy LTZ - Duramax/Allison
2008 Eagle 30.5BHS