I've spent hours on MX fluxbox, but wasn't able to make the brightness and the time adjustments permanent.
I boot it from my live USB stick by the way.
You can create a second partition on the usb stick and use that to store data. The following link is not for your distro but it should give you an idea of how to do it.
https://www.kali.org/docs/usb/usb-persistence/
You can also encrypt your second partition to keep it more secure.
This does not enable persistence on your distro, but you could write and save scripts that make all your desired changes every boot.