How much clearance is there between the supports and the the roof? Some of the pics looks neat flush, and that metal rubbing on the paint wouldn’t be good.
My thoughts are the same. When considering the force of weight added from the cargo load in addition to the flexing of the vehicle, I can see a potential for metal to metal contact.
Another consideration is the inability to clean the truck surface allowing for paint errosion.
With that mentioned, the over all concept is pretty cool.