Well, I guess I am into Phase II of the project...
After reading several things on this forum, Mr. Knox's many posts, and seeing Chaz's Flow Dynamics model of how much better the shelf makes the partial bed cover work, I decided to cook up a "Shelf" to mount under my 3rd brake light, as discussed earlier in this thread by Mr Knox.
Understanding that the angle to shoot for off the roofs 12 degrees, I decided to do a little Math (with the help of an on line calculator) to see how far out my "Shelf" would have to go to get 12 degrees off the roof line...
I found this site:
RIGHT TRIANGLE CALCULATOR and plugged in my "knowns" to find out how far back my shelf need to come off the roof:
I know the my mount point for this shelf is 2.25" below my roof line.
I know the angle needs to be 12 degrees.
Shelf distance from the cab: 10.5"
So I found a lonely chunk of 6061 T-6 aluminum in the scrap bin at work.. about 0.075" thick.... Perfect
I cut it to the width of my cab at the roof: 48" and made the piece 10.5" wide (as per the on-line Calculator), and cut it to fit around my antenna mounts.
I just mounted it to my Antenna mount rail and it is quite stiff..
I guess we will find out if it helps tomorrow...
I guess the side pieces of the inverted "C" shape will take a bit more planing...
I'll try to get a photo tomorrow in the daylight.