I'd be happy to volunteer to remotely pilot a model to very high speeds, pending approval by the powers that be...
In other words, the only way I can think of to break the sound barrier without the model pulling an insane amount of G force, is to pilot it from an actual Supersonic capable aircraft acting as a "pace vehicle".

Having had my carcass travelling at Mach 1+ at a relatively low altitude, I can say with reasonable certainty that things are occuring at a very fast rate.

As far as propellers go, you simply are not going to go super in a prop driven airplane and have it survive...