I figured the same thing, I was expecting high temps with the half fill but it hasn't happened... yet.
I have Kameari oil temp, water temp and oil pressure gauges. So far on the street, hwy running and blasts through the hills running a 4.37diff, 0.833 5th gear, with 7k shifts the oil temp is steady as a rock at 82deg in 35deg ambient temps.
No idea how that compares to a stock non filled block as the gauges were installed when the 3.1 half fill was dropped in.
I'll definitely have a temp controlled cooler before I get back to the track. Track days are a whole other world of hurt.