Thanks for all the replies, guys. The total static weight of the topper, rack, and tent comes to about 450lbs. After consulting a few other resources, I've concluded (hopefully, rightfully so!) that given the fact that the total combined weight of the topper, rack, rooftop tent, and it's occasional occupants will be spread out over all three surfaces of the bed rails I should be fine. I mean, I'm 240lbs, and I can stand on one foot on the bedrail without it deflecting, or deforming in any way. I just can't see how a static 500lbs, evenly distributed across some 15 ft or so poses any significant problem. If it was carrying that much weight, that high, and in a crosswind, I could see the issue. I hope I'm right!