I can tell you that there are thousands of oval track cars that are built using CM and were MIG welded. While we don't generally run much over 125 mph or so (except on a mile track where straightaway speeds can reach 175 mph or higher...and big miles are few) most racing sanctions require a .063 minimum wall thickness on the main cage and supports. The main frame rails on my older chassis are .049 and my newer car are .083.

Kinda funny that the lower class cars generally must run .083/.095 tubing for their cages.

Not trying to argue with anyone just sharing my experience.