I tried an experiment today. The pressure started at 440 on the high side, 130 low side, same as yesterday, similar conditions. I added water to the tray so the fan rim would pick it up as designed. WOW, the pressures dropped to 355 psi high side and 120 suction. It had little effect on the condenser outlet air temp, and air flow felt reduced, but it sure works, and continued to do so as long as I kept the tray filled so the fan water rim was in the water. When the water runs low, the pressure climbs again. So adding a water feed/float valve might be one solution. I did not test BTU performance, but I'm expecting it would improve as well.
I also did some investigation then with a fast acting thermometer in a hand held anemometer. The temperature on the air inlet at ground level was about 11 degrees above ambient, about 98F. I thought it might be condenser heat getting back to the inlet, so I turned off the compressor but left the fan on. No real change. I then tried chest vs ground level temperatures away from the unit but still with wind blocked by the shed. What's happening is that the ground is heated by the sun, and radiating that heat upward near the ground. It's less pronounced with more wind, but as wind slows near the ground I still see this solar radiant heating effect on air temperature. I'm also getting the same heating effect as I go closer to the west facing wall, but just being close to the ground is problem. There's no vegetation to insulate the earth.
Lots to consider; I didn't realize that radiant heat from the ground and close structures would have such a large effect on inlet air temperature. The built in water spritzing via fan rim cooling sure works, even though it was humid today from last nights rain. I wish I had a source of demineralized water; I expect my well water would turn the coils into a mineralized mess. My water is quite good for AZ but still pretty hard.
Apparently many window AC units use this fan ring/rim in water trick to get rid of the evaporator condensate, while boosting performance.
I'm not sure what my best approach is, yet.