Attaching Clamp Down style Thule Roof Rack to Extra Cab

Hey Taco Fans,

I've been wanting to add a roof rack for a while now. Just one bar, and then I have the "T Bar" or "Goal Post" that goes into the hitch receiver. Mainly looking to haul long pieces of lumber or a canoe. A friend recently gave me his old adjustable Thule racks. I was going to look into getting one permanently mounted, figured I'd have to get it bolted into the roof.

When I was just checking them for the width I noticed that it looks like the mounts could just clamp on above the extra cab window as is. I'm thinking once I get it adjusted and tightened up, it might just work without drilling. I feel like I'll want to put down some thin rubber or something to protect where the clamps lock in. But other than that, I'm thinking it could do the trick... Thoughts?

Thanks!