Yes that's what I am doing, I don't even know how to create another one D:
The skins are called vicz_sign. About the model: I can send you the files, but the OIV installer just adds the model in a dlc folder and doesn't replace the original sheriff files
1 & 2. I click replace and select my livery but both the pixel format and mipmap are wrong. How can I fix them?
3. I am certain that I am replacing the right livery, when I look in the .yft files it shows my livery
4. This car does support multiple liveries and I also put my livery as the first one, so even if it didn't support multiple skins it should load anyway