Moving the cooler forward and increasing the gap between it and the muffler seems the best solution.
John, my prediction is your time in the yellow is over. You might see it on steep climb out, but for the most part you will be in the green.
Bill, Larry Geiger built a heat shield and I don't recall his results, but I am pretty sure he removed it.
Regarding the wrap, Larry Baker tried it in an effort to reduce oil temps prior to moving the oil cooler. IT did not help at all, in fact, due to the wrapping of the springs, he wound up with a massive exhaust leak in flight.
Wrapping or a shield feeds a vicious circle. Either reduces the space behind the cooler for the air to exit having come through the cooler. That offsets the benefit of the wrap or shield. Moving the cooler forward and increasing the gap between it and the muffler seems the best solution.
Here's your answer Dave.John, what do you have your temp. sensor wires covered with?