just under the valance???i am going to guess and say they are going to mount to the frame and drop just below the valance,that gives me another idea i have some 1"thick cold roll i might just put to use,great idea by the way.
i am going to take a piece of 4" wide x .25" thick strap and bend it in the shape of a U just the right size so that is slips around the frame. before it goes on the frame i am going to torch a square out of the bottom of the U this will allow those pieces you see to slide in and then it can be welded on both sides into place. then slip it on the frame and weld/bolt it to the frame.
that is the plan we will see what actually happens. lol