Your link did not seem to work for me mate, the fact is you will never seal it 100%. It is a ute after all, some rubber strips from Clark Rubber. Silicon any gaps is all you can do. It will always leak water and suck in dust. Bending the spreader bar to a higher pitch can assist with water runoff too.
I'd say your post is awaiting approval as a link was attached if you are unable to see it.