Long read, but finally finished. We had 2008 Yukon XL Denali and one of the things I did not like was the AWD. It had no selector for 4WD, etc, just had full time AWD. I don't know if the 2004 is the same, but it impacted mileage and I almost got stuck once with just one front tire spinning (G80 locker in back, open diff in transfer case and open diff in front). I think the computer was supposed to apply some braking, perhaps it did and that is why I did not get stuck, only almost.
Follow the owners manual for how to setup WDH with the air shocks, some say to have it off, others on, it depends on the vehicle.
Sounds like you will be traveling with full water tanks often to have affordable water to drink (assuming you can filter for what you need to)..
Stay positive, glad you're on the mend.
