You stole that truck. At least you did with pricing in my area. Ditch the edge tuner. Figure out what injectors were put in it (stock, .30 etc..) and get EFILive. If your trans is stock then only get trans safe tuning. And if you don't like the lift kit then take it off and put stock size tires on it. Your trans will thank you if you're towing a lot. As far as how long it lasts, if you really want it to last then put it as far close to stock as you can. A small tune will be okay. The FASS and the intake are a plus for making it last. Make sure you. Change your fuel filter with a very very low micron filter and change it very regularly. The injectors still won't last forever but that will make them last longer. Also make sure your cp3 is and stays healthy. I don't see why you'd ever have to worry about how long the truck will last. Routine maintenance along with your usual wear and tear should be your only issues as long as it was taken care of before you purchased it. I'll never forget when I first got mine the miles concerned me till a guy pulled up in an LLY and we got on the subject of miles. His had 525k and a,l he had done was a new flywheel according to him. Or course it was bone stock.
If you do decide to tow with it, i would most definitely build the trans. And consider a slightly bigger turbo or a small set of twins. Of course when you start playing with air, youre playing with fire with your bottom end.