Slow coolant leak (1/8 cup over night) from behind the black plate on the front of the transmission continued.
Seeing no other possibility I replaced the by pass O ring on the back of the water pump...along with the starter while I was there. O ring did appear a bit hard and flat...especially for only being 2 years old. Every thing appears dry more than a week later with NO coolant loss. However the ambient temperature has not dropped below 50 degrees since reassembly. Remember cold engine & ambient temperature below 40 degrees were required for coolant leak to occur.
Took about 40 hours. Biggest problems were replacing the 1/4' x 3" by-pass hose on the rear passenger side of the engine (that eventually, after 8" of metal pipe and another 1/4" X 3" hose, connects to the throttle body) and finding replacements for the fuel injector plugs that crumbled in my hands during disassembly. I wasn't being rough or careless...injector plugs seem to be made of incredibly fragile "crap" plastic.
Now that I've figured out how to reach it I believe the by pass hose would only take me an hour (still a PIA) the second time around. The injector plugs turned out to be a bit more complicated. Plastic plugs I found fit the injectors perfectly and appear far more robust. Sadly they had to be modified (VERY CAREFUL drilling) to accept the metal contacts which took a bit of time to work out.
In may be a while, this time of the year, before we see temps below 40 in my neck of the woods again. I'll keep you posted should this strange coolant leak reappear.