Is hard to answer your question, as there's no direct way to know what value the murk is.
You need first to decrypt your save file somehow (I used a Discord bot), then open the decrypted file in a hex editor (I used hexed.it), then search for a value that is equals to your current murk value in-game (using 32-bit integer little-endian), the search should return some results, then you need to edit these results one by one and encrypting the save again to test it on the console (trial and error, mine worked on first attempt tho).
Also, never heard of sdimg PS4 save format.
In order to use my save your need to first resign it to your profile using either Save Wizard or Discord bot, then copy it to your PS4 without changing the file name or extension, as it's encrypted.