Once a 1-wire setup kicks in by goosing the throttle, it will continue to charge at lower RPM. The excitation is a one-shot situation, not something that requires the speed to be held above a certain level to continue to flow current. I really can't see the reason to use a single-wire hookup- - - -just use the alternator the way it was intended to be, and run one or two extra wires. The design of the internal regulator makes a big difference in how the alternator functions, as there have been at least three variations I've encountered over the past 30+ years.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!