Picking mine up in two days (2016 Tundra DC). I went back and forth on putting on rails or not then landed on not. I’m no engineer but my mind tells me that attaching the canopy, no matter how light it is, is structurally more sound to the body than the 4-5 M6 fasteners holding the rail to the body.
Reasoning? Good ole’ fashion gut feeling on what I’m comfortable with. I know hundreds have done it to rails but I’ll be trimming some unistrut to fasten into the bed between the clamps after bedrug install. This hillbilly’s 2c