Was thinking about this today and all I know is, whenever the boss replaces my ranch truck, I'ma sure gonna miss the dash on the '08 F-350 as it is the best I've ever had. The little indent is perfect for the scope to set down in to keep it from sliding. And it takes a hella rough trail to bounce it offa there.....
Life was better before they put 3-4 gang sunglass holders and 6 map lights in the headliner. You could put that shelf in where the visors go and unless you knew what you were looking for it was "out of site, out of mind" easy to have a critter-gitt'r up there all the time.
I have a shelf-it in that truck, too...... The coyote rifle up there, and the prairiedog gun on thre dash.
And one in my '99 along with a big sky 2 gun rack on the roof.
I had one of those in a Chevy I used to have. It was ok for the gun but it made the visors too low. I had to duck under them to see traffic lights. I now have a Dodge that has a screen and buttons up there so it wouldn't work at all.