The definition of yad soledes bo

As Rav Meir mentioned, there is a large gap of what the definition of yad soledes bo. One of the significant sources for this is a teshuva of Rav SZ Auerbach in Minchas Shlomo, you can read here, continuing to here, where he uses a halacha from shechita to come up with minimum shiur for yad soledes bo lechumra. The basic idea there is that it is well documented that the body temperature of a duck is 45 degrees celsius and we also know that according to all opinions, the beis hashechita is not considered to be boiling until the end of the schechita, meaning that a knife that touches the beis hashechita for sure is not treif. Thus, at this temperature we know that we have not reached yad soledes bo