Install "player" files here; use a trainer to equip all the pieces of clothing:
Grand Theft Auto V\mods\x64v.rpf\models\cdimages\streamedpeds_players.rpf\player_two

The hair in this is just a texture so you need to download this hair model for it to work:
https://www.gta5-mods.com/player/curly-hair-for-trevor

