Wear & Tear. New texture overlay on survivors.
With the new killer, the infection looks weird with no rips in the clothes, no bruises, not even blood on the penetration points. There should be at least 3 new texture overlays and tags for the cosmetics a survivor is wearing. First tags, Torso cosmetics need to be marked whether or not their shirtless. Then we get to the texture overlay to slap on top of the survivors' back and maybe front, the killers usually hit from the back.
Texture overlays.
Shirts: Survivors with shirts will receive cuts and tears on parts that are penetrated by sharp weapons or infections. The middle of the tear will just be bloody red so there is no worry about skin color unless you want these tears to remain after being healed. I'd prefer these tears to close and fade once the survivor is healed.
Shirtless: Survivors without shirts will always receive bruise marks when injured by blunt weapons. No tears will be applied as there is no clothing, just blood marks where there is penetrated points and large cuts on the body.
At least 3 textures; tears for clothing, blood spots on penetrated points, and bruises for the shirtless.
It could be like a paint brush to allow one (or two if you worry about different gender models) thing(s) to be created and be applied to all as long as the tags are applied correctly and you don't have to edit every cosmetic itself, just apply tags and make the overlay textures to slap on top or whether gesture you want to use to put it in play. This shouldn't ruin any existing cosmetics nor mimic existing ones since it'll just be its own object to wrap around on top. Tween animations can be applied if you desired when the survivor receives these marks or reversed when healed.