Are you installing Resorepless Nude Mod after you have injected the textures? If you are, Resorepless is overwriting your textures. Meta Injector should be the last thing you do before you open the game.
If everything else fails. Manually copy your pbw_00_nude_0001.dds files to "Black Desert Online/character/texture/" before launching the game.
What you can do relatively easy with my tools is to do exactly what you said you managed to do before, which is deleting a certain part of the armor, but editing the texture alpha channel.
A complete tutorial on how to do do this can be found in the first page, under the title "Removing a specific part of an armor by editing textures"
You can also paint the armor in a different color by editing the textures.
But if you want to actually add polygons to the armror, like adding a new piece, or editing the 3D model of any part of the armor, then you're gonna have to use the PAC_to_DAE_Converter_v2.zip ,which also has a tutorial in the first page on how to use it, under the title "Black Desert Online 3D Model Export / Import Tool" but it only doesn't teach you how to do 3D Editing because I don't know anything about 3D editing. But as far as converting to a readable format, and then re-importing it to the game, the first page got it covered.
About the "Remove a armor" option in this mod:
If you remove the armor by using the options to remove a .PAC file, the game will load a different 3D model instead of the actual armor, and this 3D model has a invisible texture, so it's like there's nothing there.
If you remove the armor by using the option to remove textures, the game will load a invisible texture over the armor model and it will appear invisible.
But all of those two options delete the whole armor. Like if you set to delete the upper body part, the full top part of the armor will be gone.
Let me know if I didn't answer any of your questions exactly the way you wanted to know.
