Call me impressed, the little thing works.
Could not reproduce exactly the same conditions - the sun moved and I had to transfer the camera to the window around the 20 mins mark, hence it had a little bit of more air. But was under the sun, became very hot as before.
The Ulanzi fan was used on full speed. If the footage is long, good idea to use it plugged on a power bank / USB charger, with 25 mins the internal battery was around 50% (then I plugged it in).
The yellow warning appeared on the 25 min mark, and the red around 33. And the camera never shutdown until the 128gb card is full, on the 46 minute mark.
The integrated temperature meter was kinda useless - yellow on the 39oc, red on the 42oC.
Another bad thing - even with the back film applied, the suction cups do not work very well; pressed the fan a bit to stick from time to time. Needs some "baby caring" in a tripod, and for run and gun it will fall for sure. In the Fujifilms, I would mod it to use the srews that the camera have.
To summarize, it works for tripod use, even a bit better than I expected. But have some caveats.