As a follow up to this, I replaced the thermostat, water pump and aux fan switch o-ring as well as did a full cooling system flush. This did not resolve the problem. I haven't since invested any more time in trying to figure it out. I figure come time for inspection I'm just going to have my wife do a couple short trips as usual and when the light goes off, drive it over to the inspection facility and it should pass.
I am still concerned however that I'm probably damaging my cats and perhaps not getting the best MPG I could get (although I get 20.1 combined).