RE: flying behind the flightline
That has been discussed many times and there is no reason to change the AMA rule as the allowance for a curved flight line is the correct answer and it satisfies the AMA requirement and your needs.
Since they use multiple flight lines at Muncie one can ASSUME it is within the rules. Hard to tell as there have been times when clubs were required to step up to and maintain a higher standard than was enforced at the black hole of modeling.