How to maintain custom tweaks after reboot/sleep

[MS]

As for the Overclocking, I would suggest similarly editing the files (vi/nano - most likely as root) directly vs. echoing the desired input..
*Added - on a second thought - you could go to 'session and startup' the 'application autostart' tab to add the script... Remember to make the script executable.

Also instead of vi/nano, one can open the folder(s) as administrator(rt click) and edit the files with leadpad...

I did edit the amdgpu target files couple of times but similarly as with echoing, the values get nullified on every occasion. For adding the scripts to autostart, I imagine it will apply only per boot, but what about waking from the sleep mode? Will need to test it out.