I decided to do a bit of digging for this, and learned a few things.
First of all I think that somewhere in the files is an actual nude texture, a bug was reported where the character creator failed to load any clothes and in a screencap the user took, there was actual nipples textured, which isn't super uncommon, but it still helps.
The nice thing is that the in-game model has the underwear textured on, so if we could just get both the character creator model's texture, and the in-game model's texture, it'd be really easy to make the in-game model nude.
I tried getting textures of course but, get ready for some techno babble here, The game seems to run Directx9, which would allow Umod to hook, However it loads the .dlls from the games folders, and trying to overwrite them with Umod's .dlls ended in a crash, so Umod is a no go.
There are also .dlls for Directx11, but I see no way to make the game run dx11, and even if we did, I'm sure Resorep would fall into the same trap.
Since ripping textures directly doesn't seem possible, I searched the game files, and most of the data seems to be spread between various .pak files, I couldn't find anyway to unpack them though, but I also didn't search too hard yet.
However, turns out you can run the game even without all the .pak files, so I one by one went through, renaming a .pak file, loading the game, checking what was missing and then moving onto another one.
Unfortunately, nothing too special came of it. Though I did learn that if you "remove" objectsCWop, CWpa, CWsh1 and 2 and CWso, you can sort of walk in your underwear despite being dressed, you have to get undressed first though, or you'll just be a floating head, and I'm pretty sure the same applies for other players too, nice if you're shy leaving your character in your underwear for everyone to see... Or something... I guess?
The only other interesting files were objectsCOCo, CW and CWBB, as they all unload the character model when missing. Its possible the body textures are stored in one of those 3 files, though I'm not sure if the nude texture will be there too or not. Also, GameData.pak causes the game to hang on the loading screen, so I wouldn't mess with that one.
So, put everything together and we just need to find a way to unpack and then repack one of those 3 .pak files and we'll be golden! Hopefully narrowing the field of search this much inspires people to help mod this game, as the character models are quite nice, and I think golfing in the nude would be a first.
TL;DR Nothing usable right now, but unpacking some .paks might help.