Power zener with mosfet + zener
You can easily engineer an extra MOSFET circuit that “thoroughly” shunted the MOSFET-zener follower circuit when the voltage dropped below (say) 90 volts. You could probably do it with a relay instead of a MOSFET except you’d probably worry about it switching on and off too often.

Or just use a low drop out buck converter rated at greater than 4 amps and greater than 150 volts. There are certainly buck chips that could be engineered to do this.