The cargo rail was made with these small machined spacers and some 1/16" x 1/4" aluminum strip. The ends were bent by hand and all of it was screwed on. Naturally, all the spacer block locations required thoughtful layout beforehand.
I would've loved to use countersunk screws for this rail, but when using #1 and #0 screws, some length and head configurations simply aren't available, or they are $1+ per screw. I'm a $4 per 100 kinda guy. And the smaller sizes pretty-much guarantee that you're gonna destroy 1/2 of them during installation. Amazingly, I was able to drive all the #2 slat screws in with a DeWalt impact driver and a good/sharp #1 Phillips. (the trigger has really good feel)