ORIGINAL: buzzard bait
The great thing about the approach in the old MAN article is that the sliding fin proved the point so simply and effectively. It didn't change any other relationships on the airplane and it demonstrated a proportional effect because the sliding fin could be moved up and down to any position.
I think that changing the thrust line would just start a new set of arguments. Why not start with a symmetrical cowl, show that it doesn't cause yaw, and then add side area to the cowl different amounts in different locations should give a clear picture of what, if anything, it's doing.
Jim
Of course it would... and it just might just put the focus on the primary cause of prop induced yaw on model planes, rather than chasing a possible red herring.