I just finished installing this yesterday. Props to HotShot for answering a last minute technical question almost immediately - that's customer service! I'm super happy with this rack, and of all the ones I've looked at, I'm glad the team at HotShot steered me this direction. The mounting design will allow this rack to be removed if needed and leaves only the rivet bases in place (no gaping holes in the roof of the truck). Now I just need to load it up with gear.
A few comments/notes regarding the installation instructions that I downloaded: They list (42) 1/4" flat washers when in reality there are (36) 1/4" BLACK flat washers and (8) 1/4" STAINLESS flat washers. Additionally, there are (8) M8 flat washers that are not listed in the instructions. They do not mention needing a 13mm wrench, but you will need that for installing the M8 bolts that attach the mount brackets to the rivet bases.
Finally, the detailed instructions state to drill a 13/64" hole, while the list of needed parts lists a 3/16" drill bit. I would recommend using the 3/16" drill bit because you will likely end up just a little bit sloppy during the drilling process (it is an awkward position standing on a ladder and trying to drill cleanly) - the rivets will fit snug with the 3/16" hole and you'll have a good solid connection. I would recommend leaving the rivet bases in place when drilling the holes because even with a good center punch it was difficult to perfectly align the holes with how the bases fit into the gutter - having them in place made a much better drill guide. I also used a wood block as my drill stop (sized the correct thickness to allow my drill bit to only extend the length of the rivet body) and that came in handy for tapping the rivets into place as well since things were just snug enough.
Oh, and one last thing - the FRONT holes of the REAR rivet bases will encounter two layers of metal that you will drill through. All the other holes only go through one layer, and that was the reason for my last minute question to HotShot in the middle of the installation.