My JCR Rack works. I can't just start off by rolling up the cover because the metal end bar of the tonneau when flipped up is too wide for the angled-in verticals on the rack. The rack is wide enough at the bottom but narrows quickly as it goes up.
But it's not a big deal. Instead of rolling it from the start I just angle the tonneau end bar back on one side until I clear the rack uprights. Then from there, roll as usual. The roll rests nicely against the front rack uprights.
Check out our T-Series 18.5" alternate. It is adjustable every 2" all the way down to 12.5" so you can choose between height and how easy it is to open the cover.