Hey Airmapper, I dig the original roof rack design but was wondering about the mounting. Did the ubolts hold the weight very well? Most designs I've seen run a bar across the top of the factory rails that disperse the weight across the length of the factory rail, but I dig the low profile look of your design and that the factory bars are still usable for other mounts.
It has held well over 400lbs without indication of stress, which is really more than is safe to drive with at that height. The stock tubes seem to distribute the weight well.
I will say the dampening u-bolts, padded with silicone sheet, serve a double purpose. They cushion the load, and prevent you from crushing the tube, which will weaken it. Those U-bolts do not even need to be very tight to secure the load, just snug to the tube to prevent movement.
If you look the bolts are positioned relatively close to the points where the stock tubes attach to the roof. They also have a support in the middle, so the stock tube is dispersing the weight across the roof of the vehicle. The only question would be the strength of the tubes, I've not seen any indication yet that any load I've subjected to it has been enough to stress it. If I ever do see that I'll be sure and make note of it.
Ideally though, I'd avoid having more than say 150-200lbs up there while the vehicle is in operation.
I currently have the basket type rack removed and have a crossbar arrangement installed I fabbed using the same style dampening u-bolts. It holds my RTT and awning very securely. My only gripe right now is my RTT sits a shave higher than I like, if anything I'd like to tuck it down in between the rails some.