Get the H&S MiniMaxx so he can change tunes on the fly when he is not hauling a load it will also show 4 gauges on the screen at once. I have mine setup for EGT, Trans Temp, Oil Temp, Coolant Temp. They sell a mount (color match is 45 days out right now I think) or BlendMount makes a nice under mirror mount that is firm which I think I might switch too myself. More guys will be able to help with trans settings once you get it. Also can't do your DPF delete without some sort of tuner so its not optional at that point.
Intake will definitely help, if there is no emissions in your area get a nice exhaust that goes 4" all the way back and no cat/dpf. since he is hauling he will probably want a muffler on it. A lot of the towing members are recommended the downpipe to help drop EGT's while hauling, as well as a 3" CAC pipe for the intercooler (if you've popped the hood you've probably seen that junk). You can take it to the next step and do full intercooler as well as water/meth as well if you wanted