Cool, greetings to Berlin from a former Ruhrpottler and Landsberg am Lech‘ler :-)
The space you have between the crossbars and the brackets (circle) was exactly what I didn‘t want to have. As we‘re taking quite some rough roads I didn‘t want to have the awning swinging.
If possible I would try to push it back towards the crossbars.
I used all 3 brackets and yes: I hid the M12 between the awning and the bracket. Wasn‘t easy, but eventually I was able to countersink a flat head into the bracket + into the extruded profile.
Don‘t have the full „holding strength“, but still adding a significant amount of safety.
Will take a pic once I take the awning down again