Boost converter as high-side MOSFET driver
If you are using a boost converter IC it should have feedback so it will regulate its own output voltage, so it won't just rise forever.

You might want to replace the boost converter with a voltage doubler. Check figure 7, you can generate the clock signal with your microcontroller to save on part count. Since you are only charging up the gate of the MOSFET you don't need very much current. You will probably need a bleed resistor to make sure the MOSFET turns off eventually, but it can be very large.