Because the supply will be as high as 30 volts the Vgs voltage on the mosfet must be clamped below 20 volts.
Modification using a 5 volt zener diode to protect Q1.
View attachment 299621

This is a nice circuit and all values are spot on. Just one thing: pin 6 should be directly connected to pin 1, otherwise voltage on pin 6 will never drop below Vref and there will be only one threshold for both On and Off conditions (when pin 1 is low, pin 6 will see voltage divider R5-R6)

 

For the sake of diversity, here is another one, using no ICs:

A bit less temperature stable.
Having TL431 definitely bits it in temperature stability.

 

Just one thing: pin 6 should be directly connected to pin 1,

Thanks for catching that mistake.
Schematic edited in post #18.

 

For the sake of diversity, here is another one, using no ICs:
View attachment 299675
A bit less temperature stable.
Having TL431 definitely bits it in temperature stability.

thanks a lot