Thanks for the very complete answer, Brit312. As I gather, Mr Vortex is a relative novice (from the profile, I'm making an assumption), an additional point. As supersonic flight was overwater, the loss of all engines above M1.2 pretty much precluded a airport landing except for initial acceleration and final deceleration. And, at that, initial acceleration would require a 180 degree turnaround, probably reducing the time above M1.2. Over sovereign land, you would, I presume, be going directly to the slower than M1.2 drill and the possibility of an airport landing.
GF