Ok back to the task at hand.... Good chance I'll still have to use my Thule load bars for the time being (although I love the direct mount idea). Here's another concept that i like for a few reasons:
1) Doubles the mounting bolts = stronger and a lot more work to remove
2) Wider foot print for the mounts
3) Don't need to drill hole through load bar = easier adjustments

Downside is about double the cost (due to material scrap mostly... can order in 1' or 3' sections and only need a 20" section to make 6 mounts). But then again i'm sure I'll have a few prototype pieces anyway... so even if i go with the 2" mounts I'll probably want to get the 3' material regardless for mistakes and modifications to the design.