I'd say DXT5 and interpolated alpha is wrong...
From
here, Tracker123 says car skins are to be saved in DXT3 with explicit Alpha:
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These are not the default settings but for this skin to work you need to change them to the settings that are on this picture, the only changes are Generate 11 Mipmaps and the filetype should be DXT3 ARGB with Explicit Alpha.
--------You should give it a try for ragdoll - I'm not sure Mipmaps are necessary in this case.
You can also check original ragdoll skin and see how they're saved - I don't know if File->Properties->Details in file explorer is enough (I'm not on my PC right now, so I can't tell) - if not, you'll need external tool to check)