Any qualitative analysis saying RC snubber required or not for High current Buck converters
Have you considered that the parasitic diode inside the lower mosfet (in a synchronous buck) will conduct and reduce the projected (-)141V you mention? There is also the parasitic capacitance of the inductor which will also tend to reduce this "spike" and convert it to a decaying sinewave until the lower mosfet turns on.

Regarding your "one more question" I think a link may be missing (here LL)?