That’s really cool could you use a ratchet strap instead or do you think that would damage the gutters ... would you trust putting a Jerry can up there
A ratchet strap might be over-kill in this situation. The Rightline system lined above uses a basic plastic buckles/tension-lock. I used metal spring buckles for added safety, they don't slip as much, and I used a metal lock, making it adjustable, and not requiring sewing.
The ends of the 4 strap have a loop sewn and girth hitch into the inside roll bar providing a very solid anchor. It comes out the door at these angles:
I'm not concerned about the roof gutter at all, it is a compression force inwards on the gutter, and there isn't enough tension in the strap to cause a problem. There is no need to ratchet it up, all the straps need to do is keep the bags from sliding off and moving around, due wind resistance or side to side off-road action, with the weight and friction of the bags on the roof providing a good amount resistance force. With the three bags, the inner one doesn't get much downwards force at all and sometimes is pushed back by wind till the bag's handles/straps catch.
One area of concern is the total weight on the fiberglass canopy, you can see it flex a bit in the middle, when loaded. So if you ratchet it up and thus apply excessive downward force it might add to the problem. However, my bags rub against each other and I can see evidence of hot spots.
In hard core, prolonged off road trails, what kills roof racks is the violent side-to-side action, and what fails is not the roof rack, but the legs/attachments. This is one reason I wanted to try this system because there is no rigid attachments to fail. But I don't have enough experience with this system in that environment.
Looking at the Rugged Ridge pictures, looks like JLU, is the gutter running all the way back on the JLU? My JKU has gutters only over the doors! Looks like there is a connector to the gutter. I can't visulise how that works. I would be a bit concerned about that. Strapping down to the roll bars seems more secure.
I wouldn't put a jerry can up there, need to keep weight as low as possible. Jerry can would go inside the cabin, a military spec one shouldn't release odors, or I read folks recommending putting the jerry can inside a trasharoo back tire carrier. An empty jerry can, sure, on the way home to keep it out of the way. There are so many light things that can go up three.