I have used a Thule box and their attachments for several BMWs, VWs, & Mercedes.

I have a trip comming up in a few weeks and since Thule does not offer a rack for the E60 I bought the BMW Roof Bars. The Thule boxes just clamp down on the Thule steel bars, but before I do this and drive 1000 mi I would like to know how the BMW Roof boxes attach to the roof bars, anyone?

The BMW bars are aluminum and I fear the Thule mount system will bend the BMW bars - and I can't spent $1000 on a new box right now. Any help appreciated!