So to summarize so far: There are now several people here who have EXACTLY the same issue. That of course is only members who are actually posting here, but I've also read about a couple others in one the Facebook groups.
The EXACT cause and SPECIFIC fix has
not been determined. Upgrading to the green belt is not a fix and spraying belt dressing is only a
temporary fix. Rippa is suggesting a bad tensioner or idler (i.e. defective factory part) but being there are several with this squeal, customers are less inclined to throw more money at parts that may or may not "fix the problem."
Personally, IF I keep the incognito I may consider trying the
Metco 3 piece idler pulley kit to reduce some rotational weight and have potentially better bearings. I may also just pull off the incognito and enjoy the truck the way it was meant to be without the embarrassing squeal.