Thule or Yakima Tracks Directly to Cab
We installed Thule (or Yakima, I can't remember which) directly to the roof of the cab on our 2004 DC. We mounted them as far outboard as possible to get the weight over the pillars and off the potentially weaker sheet metal of the inboard sections of the roof. We backed up the mounting screws with large washers and sealed everything well with silicone. While we've had no problems with leaks (over the last 6 years), we did decide to move or Maggiolina back to the shell from the cab (the shell has a custom built interior metal frame to take weight off the fiberglass).
From this configuration:
To this configuration:
We did that because over time and many miles on washboards and rocky roads we noticed some that some squeaking developed somewhere between the Maggiolina, crossbars, tracker feet, tracks or cab of the Tacoma. I was worried that the constant side to side motion of the 130 pound Maggiolina might be loosening the mounting hardware, enlarging the holes, or otherwise increasing the likelihood of a leak or stressing the cab. We now carry our solar panels on the cab and the Maggiolina on the shell. No squeaks and slightly better mileage possibly due to better air flow.
There were two things that were difficult in mounting the tracks to the cab. The first was removing the headliner (we actually never did get it out of the cab, we had to work around it once we lowered it from the top) and the second was actually drilling holes in the top of our then-new-to-us truck when it had only 23 K miles!
Howard L. Snell