I'm not sure that your analysis of what's going on is correct. I don't know, but I'm not sure...if you know what I mean.
When the aircraft is in a stable side-slip, one would assume that it is descending. The wing loading will be reduced and the stall put back to comfortable distance from the airspeed over any part of either wing. Furthermore, a proportion of the aircraft's weight will be cushioned on the lower fuselage side, further reducing the chance of a stalled wing.
My reservations however, are in two parts. One, it would be difficult to assess the load on the tail without very skilled calculations. Two, the engine temps may not be showing some hidden parameters that they were never intended to display. But, I have seen huge loads on our brick built BAC1-11's tail, due to the strangest of occurrences. And I have seen the engine parameters showing extraordinary fluctuations due to other circumstances. During prolonged and repeated side-slips, I never saw the slightest variation in temps, just a little change in EPR