Had to go home a different way but still a valid sample. This one includes some freeway driving. Yep. Port Hueneme, my desk is on station.
Some of my observations:
1) It's interesting that the TStat opens at about the same run time even though my engine started 30F warmer
2) I think it's cool that when the TStat first opens, the coolan in the rad is super cold and drops the temp quite a bit, then as the aluminum rad heats up, the temp goes to 200F plus or minus 5.
3) My engine runs cooler at lower than 25MPH because my fan runs at that temp.
4) When I left home this morning, it was 70 degrees and sunny. When I get to work it was 68 and sunny. When I left work it was 74 and sunny. When I shut my truck down in Oxnard this afternoon, it was high 70s and sunny, no breeze. I did not get dew point or humidity measurements.
You guys all put some good stuff in these comments! The answer isn't as simple as I thought it would be! I'm excited to see what happens when I pull the TStat.
For the record, if coolant temp goes over 210 during the "No TStat run" I will pull over, pop the hood, and let it cool down. That will be a successful test showing it will over heat without a TStat.