When the camper is set up, all of the weight of the camper and the occupants passes through to the roll bar. The weight is evenly distributed over six mounting points.  When the camper is closed, the weight of the camper roof, traction boards, etc., is supported by the rain gutters. This is approximately 100 lbs if traction boards are on the roof. The roll bar still supports the weight of the bed platform, mattress, and slide rails.  The weight is evenly distributed over the entire length of the rain gutters. If you compare this to OEM and aftermarket roof racks, you will see that they are rated to a higher weight, with the weight distributed over a much smaller portion of the rain gutters.