Those are sweet racks. They load the roof though, through the suction cup feet.
the load would be spread out mind you.... and right on the curve.
I do have an old gutter mount rack here, with the separate cross bars. Its a "Ranger-rack"! With the windows cut into the walls of my panel, I'd be afraid to get up there only supported in four places on the gutter. The pillars on my panel are wood, and the steel skin has almost no strength, as it has been collapsed sever times by the looks of it. The steel is stretched, and was just as happy to be an "innie" as an "outie" until I dinged (and filled) it back into sort of shape.
It would make camping pretty easy and awesome though. Just climb up the ladder to the loft! I guess the acid test would be to mount the rack, and put some plywood on it, and just step off the ladder...
