Chassis tube wall thickness ?

My anti-sway bar was bolted with the wrong bolt, which resulted in stripped threads. I just contemplate what are my options to fix this mess: bigger hole, heil-coil of rivet nut.

Depending on how much material is available not all fix are possible, any idea on what is the wall thickness of these tubes?

 

400i, but I presume the chassis from the whole serie (365, 400, 412) are using the same material.