This is my personal vehicle, a 2006 Toyota Prius. I originally installed a Yakima Q Towers roof rack. It worked as it should and was not permanent. The Thule Side Arm upright bike rack and the Thule Spirit cargo box both fit easily on 58" crossbars. The Spirit has been discontinued, which is unfortunate. It was my favorite cargo box.
Then I installed a Thule Aero Foot roof rack just to be able to compare Thule vs. Yakima. The required Yakima bars were 58" long, but only 50" for Thule. The Thule rack has a shorter distance from the front bar to the rear bar (24" vs 32"), but supported more weight. The Yakima rack is easier and quicker to remove but the Thule rack is slightly easier to install. The clips for all Thule racks are coated as to not scratch the paint. The Yakima clips are not.
We do tons of custom installations every year and it was time for me to put my skills to the test. I planned on permanently mounting the Yakima Control Tower roof rack. I would be able to take the rack off and on super easy and set the bar spread distance to my liking. I liked the round bar because it is much easier to work with on a rounded roof like the Prius. I chose to mount the front bar within a few inches of where the Q Towers and Aero Foot racks were mounted on the Prius. I put the rear bar 30" back from the front bar. This is more than adequate.
This is the Yakima Landing Pad #7 mounting hardware for the Control Tower roof rack. Relatively basic except for the parts on the bottom left. The silicon is all that is needed to properly seal the holes and prevent any leaks.
Here is a closeup of the hardware and how it works. It is not an easy task to thread the bolt.
The whole process can be a little nerve racking. Getting precise measurements to match up on both sides is tricky. I chose not to remove the headliner which meant I was drilling blind. This is always a big risk. Its hard to tell if you are going to drill into a frame support.
The finished product:
It was well worth the effort. Its now 5 years later and the roof racks works perfect. Super strong and no leaks. I regularly carry and cargo box and/or a bike rack. I check it periodically and I have a box of spare parts. I haven't had to make any adjustments.