Note: I am not responsible if this gets you banned online. Etc. blah blah.
That said, I use this online.
Using OpenIV:
Put mp_fm_skin_f_lo_whi.ytd (color map) in folder:
GTA V > update > x64 > dlcpacks > patchday4ng > dlc.rpf > x64 > models > ped_mp_overlay_txds.rpf >
Put lowr_015_r.ydd (Changes normal/spec maps) in folder:
GTA V > x64v.rpf > models > cdimages > streamedpeds_mp.rpf > mp_f_freemode_01 >
Wear the a bikini from the original game (Non-expansion).
Credits:
Aephrosi