You can always try using OPL with games from an SMB share, which can then be compressed with the host OS's on-the-fly compression (if available). I have 364GB of PS2 ISOs on my old Windows share (which, after moving to an HDD setup, is just used for storage now) and they only take up 271GB of actual disk space (and NTFS compression is not anywhere near efficient).
Chip-free/MC-free homebrew <3
FMCB 1.93 on MC for emergencies, NA
250GB HDD/FHDB 1.93/OPL 0.9.2 (GSM and non-GSM)/PS2 games, NO HDDOSD
80GB HDD/FHDB 1.93/POPStarter rev12/OPL644/GSM0.37/PS1 games, NO HDDOSD
SCPH-75001 (sitting idle, slims suck):
FMCB 1.92 on MC