Installation:

1: Install this mod:
https://www.gta5-mods.com/vehicles/mapped-tanker-trailer-replace-liveries-template

2: Extract the "tanker_sign_4.dds" file

3: Using OpenIV with Edit Mode enabled, add it to "E:\SteamLibrary\steamapps\common\Grand Theft Auto V\mods\update\x64\dlcpacks\tankertrailers\dlc.rpf\x64\levels\gta5\vehicles\vehicles.rpf\watertanker.ytd"