About a three hour job for me.
Only 16 torx screws of all the same size. Need a T30 screwdriver (i used a 6" T handle). First I loosened up the 16 bolts in first pic. Nuts are secure on backing bar and no wrench needed. I stood cover up and opened to about 90° in picture 2 with arrow. Try not to drag the cover when moving. The side molding starts coming off. I had to reattach it in 2 spots after I finished.
With cover open to about 90° remove tension bar (white arrow below-no tension on bar at this 90° opening position). Bolts were removed from one side and then the other. I marked rod with a sharpie for reassembly reference.
Hinge was removed and plastic/rubber hinge cover popped out of hinge with flat screwdriver. If my seal fails, I will probably cut cracked rubber off plastic pieces and glue the garage door gasket to it. Old PN is on seal below. I used a little WD40 in each hole before reassembly.
Next step is I cut garage door seal with kitcen shears to 54" length and cut off outside ridges off it with carpet knife due to thickness. Easy to do. I laid gasket on hinge and made sure there was enough rubber to cover outside plastic pivot point (see left yellow arrow below). Started with top bolt and used carpet knife to put a small hole in new gasket for bolt to start. The ridges on the gasket helped to maintain a staight line along length of hinge as I worked down length of the first cover. Tension bar goes back on in last step after gasket is on both covers. First pic below is first half tonneau cover with holes up to add all bolts and snugged down as I centered the gasket. Ridges help to center it. Started on 1 end and went to next hole and continued to the end. Cut the new rubber to length before last bolt put in so it covers the plastic pivot piece slightly (it has a slight recess- see pic below with left yellow arrow). I think finished length of rubber is 52 1/4".
Flipped up for bolting second half with gasket inside and only a slight cut into rubber for each bolt. Last step is putting tension bar back on.
The seal I used can make 2 of these. I made a mistake on the first attempt, cuting it too short. I have emailed a request to Ideal Door to see if the rubber is UV resistant. I will add additional info as to how it is holding up as time progresses. To me. it is better than it was. Tight fit like original, a little thicker than OEM material, looks better then it did, and cost effective. Not too hard to do. And, you can always put the old one back in if needed. Hope this helps.