Install "player" files here; use a trainer to equip all the pieces of clothing, the ammo vest is under accessories 1:
Grand Theft Auto V\mods\x64v.rpf\models\cdimages\streamedpeds_players.rpf\player_two

DK's backwards hat needs this model to work:
https://www.gta5-mods.com/player/trevor-s-baseball-cap-backwards-degenatron

then install "props" files to:
Grand Theft Auto V\mods\x64v.rpf\models\cdimages\streamedpedprops.rpf\player_two_p