I will agree the slip angle likely makes minimal difference in engine cooling.
I WILL say a high slip angle makes the tug come down pretty fast with not a lot of airspeed, adding some "G load" at the same time helps as well.
Airspeed (straight on or angled) is still flow through the cylinder fins.
So.......lower speed and slightly reduced airflow can only help, the slip adds to sink rate. That IS part of the goal....correct?
Turnaround time, lack of adding to maintenance..........right?