Hacking Gateway and saves

[Shadowfied]

I'm about to go insane here. I've tried for hours and hours to get MY Majora's Mask save files from MY real cart and use them with Gateway. I dumped my own cart and the .sav. Tried renaming the sav to it's corresponding titleid and placing it in root, then booting my dumped ROM using Gateway, but it always tells me the save is corrupted and it deletes it. I have managed to get some other games to work, not with .sav files though, only a few games where using SaveDataFiler and exporting, then importing and deleting the Secure Value worked.

Is there any way to get this to work or are the saves encrypted to hell or what's going on?

Edit: I know it's also related to headers, but even extracting my own identical Majora's Mask header and applying it to the 3dz still tells me it's corrupt.