Years ago, the Chattanooga Dam Triathlon in the late 1990s used to do an out and back, basically about 300 yards away from and parallel to a big bridge there. The Olympic distance race was 750 meters out and 750 meters back, the swim lined with a rope that had milk jugs tied on it. super easy to spot, and no current assistance. That race, had two different transition zones, if memory serves me correctly. I loved the swim, since it used zero energy to spot.

Why not that for the 70.3 and make it rectangular?