If the intent of the rule is that "the chain must pass inside the main frame rails at the motor plate area where the upright for the roll cage usually connects", then that's how it should read, then there's no "gray area" to exploit, and no confusion as to what defines the main frame rail. You know Dad's gonna look for the loophole; not neccesarily to take advantage of it, but to show you the potential for misunderstanding of our Mother Tongue...
