You could always swap windshields with one of these.

 

The Ford catalog calls for 22's on the 08 F-350, part number 8L3Z17528A... Part number 4U2Z17528KA if you need winter blades.

 

The reason for the discussion, and the confusion, is because Ford changed the specified length of the wiper blade, without making any change to the windshield size, slope, contour, angle, or cab that the windshield is mounted in, for 18 production years... from the early 1999 models manufactured in 1998, to the 2016 models that are winding down now as this is written.

My owner's manual specifies 20" blades. They work fine, and they were what was on my truck when new, but they don't cover as much as glass area as larger blades. A two inch difference, when swept across the entire arc of travel, covers quite a bit more glass area.

What is "confusing" to some people, like me, who "follow the book" like you suggest, is that the book specification changed at some point, without the truck changing. Hence, the "discussion" is to verify and clarify that the changed specification will work OK on similar trucks with the older specification.

No, we wouldn't install a 6.2L injector in a Powerstroke. That's just silly. However, we would put Mercon V in an older transmission that originally specified Mercon, even though our older books say Mercon. Ford changed the specification with an improved fluid for newer model years, and then told us to use the newer specification in our older transmissions, without recalling all of our owner's manuals for a reprint.

That would be a more closer metaphor to the wiper blade discussion.