The roofs on our 'runners aren't exactly up to the task of handling much weight. After I pulled a headliner from a junkyard 'runner to grab a few items, I noticed that there is literally just a small "c" shaped piece of metal that works as a doubler for the factory racks mounting hardware ( riv-nuts).

I was ready to get a Sherpa rack system for my Tepui RTT but after seeing how flimsily our roofs are, there's no way I'm climbing my 235# body on top of the stock roof. I honestly wouldn't feel safe hauling the RTT up there, even though some do it. The stock cross bars will barely hold the weight of the tent by itself, no way they're going to support a person inside of the tent. Even with an aftermarket rack system spreading out the weight a bit, it's still only being supported by a thin piece of sheet metal. There needs to be a physical tie-in between the factory rack "doubler" and the side of the roof skin where it curves downwards on the sides of the upper body.