I decided to build a shade to see if that would improve anything.
To my surprise, with the tarp shade, the power consumption of the air conditioner while it was running did not change much but the duty cycle of the air conditioner's "on" cycle, shortened.
That worked so well that I spent $100 on a couple sheets of grey PVC lattice and channel pieces. I built a more permanent trellis shade that looks nice and still shortens the A/C duty cycle during the evening sun hours.
This shade results in a 1.9 kWh/day air conditioner energy savings with the added benefit of looking less like a crime scene than the tarp.